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PCREAPI(3)									       PCREAPI(3)

NAME
       PCRE - Perl-compatible regular expressions

PCRE NATIVE API

       #include <pcre.h>

       pcre *pcre_compile(const char *pattern, int options,
	    const char **errptr, int *erroffset,
	    const unsigned char *tableptr);

       pcre *pcre_compile2(const char *pattern, int options,
	    int *errorcodeptr,
	    const char **errptr, int *erroffset,
	    const unsigned char *tableptr);

       pcre_extra *pcre_study(const pcre *code, int options,
	    const char **errptr);

       int pcre_exec(const pcre *code, const pcre_extra *extra,
	    const char *subject, int length, int startoffset,
	    int options, int *ovector, int ovecsize);

       int pcre_dfa_exec(const pcre *code, const pcre_extra *extra,
	    const char *subject, int length, int startoffset,
	    int options, int *ovector, int ovecsize,
	    int *workspace, int wscount);

       int pcre_copy_named_substring(const pcre *code,
	    const char *subject, int *ovector,
	    int stringcount, const char *stringname,
	    char *buffer, int buffersize);

       int pcre_copy_substring(const char *subject, int *ovector,
	    int stringcount, int stringnumber, char *buffer,
	    int buffersize);

       int pcre_get_named_substring(const pcre *code,
	    const char *subject, int *ovector,
	    int stringcount, const char *stringname,
	    const char **stringptr);

       int pcre_get_stringnumber(const pcre *code,
	    const char *name);

       int pcre_get_stringtable_entries(const pcre *code,
	    const char *name, char **first, char **last);

       int pcre_get_substring(const char *subject, int *ovector,
	    int stringcount, int stringnumber,
	    const char **stringptr);

       int pcre_get_substring_list(const char *subject,
	    int *ovector, int stringcount, const char ***listptr);

       void pcre_free_substring(const char *stringptr);

       void pcre_free_substring_list(const char **stringptr);

       const unsigned char *pcre_maketables(void);

       int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
	    int what, void *where);

       int pcre_info(const pcre *code, int *optptr, int *firstcharptr);

       int pcre_refcount(pcre *code, int adjust);

       int pcre_config(int what, void *where);

       char *pcre_version(void);

       void *(*pcre_malloc)(size_t);

       void (*pcre_free)(void *);

       void *(*pcre_stack_malloc)(size_t);

       void (*pcre_stack_free)(void *);

       int (*pcre_callout)(pcre_callout_block *);

PCRE API OVERVIEW

       PCRE  has  its  own  native  API, which is described in this document. There are also some
       wrapper functions that correspond to the POSIX regular expression API. These are described
       in the pcreposix documentation. Both of these APIs define a set of C function calls. A C++
       wrapper is distributed with PCRE. It is documented in the pcrecpp page.

       The native API C function prototypes are defined in the header file pcre.h,  and  on  Unix
       systems	the  library  itself  is  called  libpcre.  It can normally be accessed by adding
       -lpcre to the command for linking an application that uses PCRE. The header  file  defines
       the  macros  PCRE_MAJOR	and PCRE_MINOR to contain the major and minor release numbers for
       the library.  Applications can use these to include  support  for  different  releases  of
       PCRE.

       The  functions pcre_compile(), pcre_compile2(), pcre_study(), and pcre_exec() are used for
       compiling and matching regular expressions in a Perl-compatible manner. A  sample  program
       that demonstrates the simplest way of using them is provided in the file called pcredemo.c
       in the source distribution. The pcresample documentation describes how to compile and  run
       it.

       A  second  matching  function, pcre_dfa_exec(), which is not Perl-compatible, is also pro-
       vided. This uses a different algorithm for the matching. The alternative  algorithm  finds
       all  possible  matches (at a given point in the subject), and scans the subject just once.
       However, this algorithm does not return captured substrings.  A	description  of  the  two
       matching  algorithms  and  their advantages and disadvantages is given in the pcrematching
       documentation.

       In addition to the main compiling and matching functions, there are convenience	functions
       for  extracting	captured substrings from a subject string that is matched by pcre_exec().
       They are:

	 pcre_copy_substring()
	 pcre_copy_named_substring()
	 pcre_get_substring()
	 pcre_get_named_substring()
	 pcre_get_substring_list()
	 pcre_get_stringnumber()
	 pcre_get_stringtable_entries()

       pcre_free_substring() and pcre_free_substring_list() are also provided, to free the memory
       used for extracted strings.

       The  function  pcre_maketables() is used to build a set of character tables in the current
       locale for passing to pcre_compile(), pcre_exec(), or pcre_dfa_exec(). This is an optional
       facility that is provided for specialist use. Most commonly, no special tables are passed,
       in which case internal tables that are generated when PCRE is built are used.

       The function pcre_fullinfo() is used to find out information  about  a  compiled  pattern;
       pcre_info()  is	an  obsolete version that returns only some of the available information,
       but is retained for  backwards  compatibility.	The  function  pcre_version()  returns	a
       pointer to a string containing the version of PCRE and its date of release.

       The function pcre_refcount() maintains a reference count in a data block containing a com-
       piled pattern. This is provided for the benefit of object-oriented applications.

       The global variables pcre_malloc and pcre_free initially contain the entry points  of  the
       standard  malloc()  and	free()	functions, respectively. PCRE calls the memory management
       functions via these variables, so a calling program can	replace  them  if  it  wishes  to
       intercept the calls. This should be done before calling any PCRE functions.

       The global variables pcre_stack_malloc and pcre_stack_free are also indirections to memory
       management functions. These special functions are used only when PCRE is compiled  to  use
       the  heap  for  remembering  data,  instead  of recursive function calls, when running the
       pcre_exec() function. See the pcrebuild documentation for details of how to do this. It is
       a  non-standard	way  of  building PCRE, for use in environments that have limited stacks.
       Because of the greater use of memory management, it runs more slowly.  Separate	functions
       are  provided  so that special-purpose external code can be used for this case. When used,
       these functions are always called in a stack-like manner (last obtained, first freed), and
       always  for memory blocks of the same size. There is a discussion about PCRE's stack usage
       in the pcrestack documentation.

       The global variable pcre_callout initially contains NULL. It can be set by the caller to a
       "callout" function, which PCRE will then call at specified points during a matching opera-
       tion. Details are given in the pcrecallout documentation.

NEWLINES

       PCRE supports five different conventions for indicating line breaks in strings:	a  single
       CR  (carriage  return)  character,  a  single  LF  (linefeed) character, the two-character
       sequence CRLF, any of the three preceding, or any Unicode newline  sequence.  The  Unicode
       newline	sequences  are	the three just mentioned, plus the single characters VT (vertical
       tab, U+000B), FF (formfeed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028),
       and PS (paragraph separator, U+2029).

       Each  of the first three conventions is used by at least one operating system as its stan-
       dard newline sequence. When PCRE is built,  a  default  can  be	specified.   The  default
       default	is  LF, which is the Unix standard. When PCRE is run, the default can be overrid-
       den, either when a pattern is compiled, or when it is matched.

       At compile time, the newline convention can  be	specified  by  the  options  argument  of
       pcre_compile(), or it can be specified by special text at the start of the pattern itself;
       this overrides any other settings. See the pcrepattern page for	details  of  the  special
       character sequences.

       In  the	PCRE  documentation  the word "newline" is used to mean "the character or pair of
       characters that indicate a line break". The choice of newline convention affects the  han-
       dling  of the dot, circumflex, and dollar metacharacters, the handling of #-comments in /x
       mode, and, when CRLF is a recognized line ending sequence, the match position  advancement
       for  a non-anchored pattern. There is more detail about this in the section on pcre_exec()
       options below.

       The choice of newline convention does not affect the interpretation of the \n or \r escape
       sequences,  nor	does it affect what \R matches, which is controlled in a similar way, but
       by separate options.

MULTITHREADING

       The PCRE functions can be used in multi-threading applications, with the proviso that  the
       memory  management  functions pointed to by pcre_malloc, pcre_free, pcre_stack_malloc, and
       pcre_stack_free, and the callout function pointed to by pcre_callout, are  shared  by  all
       threads.

       The compiled form of a regular expression is not altered during matching, so the same com-
       piled pattern can safely be used by several threads at once.

SAVING PRECOMPILED PATTERNS FOR LATER USE

       The compiled form of a regular expression can be saved and re-used at a later time, possi-
       bly  by	a  different  program, and even on a host other than the one on which it was com-
       piled. Details are given in the pcreprecompile documentation. However, compiling a regular
       expression  with one version of PCRE for use with a different version is not guaranteed to
       work and may cause crashes.

CHECKING BUILD-TIME OPTIONS

       int pcre_config(int what, void *where);

       The function pcre_config() makes it possible for a PCRE client to discover which  optional
       features  have  been  compiled into the PCRE library. The pcrebuild documentation has more
       details about these optional features.

       The first argument for pcre_config()  is  an  integer,  specifying  which  information  is
       required;  the  second  argument  is a pointer to a variable into which the information is
       placed. The following information is available:

	 PCRE_CONFIG_UTF8

       The output is an integer that is set to one if UTF-8 support is available; otherwise it is
       set to zero.

	 PCRE_CONFIG_UNICODE_PROPERTIES

       The output is an integer that is set to one if support for Unicode character properties is
       available; otherwise it is set to zero.

	 PCRE_CONFIG_NEWLINE

       The output is an integer whose value specifies the default character sequence that is rec-
       ognized	as  meaning  "newline". The four values that are supported are: 10 for LF, 13 for
       CR, 3338 for CRLF, -2 for ANYCRLF, and -1 for ANY.  Though they are  derived  from  ASCII,
       the  same  values  are returned in EBCDIC environments. The default should normally corre-
       spond to the standard sequence for your operating system.

	 PCRE_CONFIG_BSR

       The output is an integer whose value indicates what  character  sequences  the  \R  escape
       sequence  matches  by  default. A value of 0 means that \R matches any Unicode line ending
       sequence; a value of 1 means that \R matches only CR, LF, or  CRLF.  The  default  can  be
       overridden when a pattern is compiled or matched.

	 PCRE_CONFIG_LINK_SIZE

       The  output  is	an integer that contains the number of bytes used for internal linkage in
       compiled regular expressions. The value is 2, 3, or 4. Larger values allow larger  regular
       expressions  to	be compiled, at the expense of slower matching. The default value of 2 is
       sufficient for all but the most massive patterns, since it allows the compiled pattern  to
       be up to 64K in size.

	 PCRE_CONFIG_POSIX_MALLOC_THRESHOLD

       The  output is an integer that contains the threshold above which the POSIX interface uses
       malloc() for output vectors. Further details are given in the pcreposix documentation.

	 PCRE_CONFIG_MATCH_LIMIT

       The output is a long integer that gives the default  limit  for	the  number  of  internal
       matching  function  calls  in  a  pcre_exec()  execution.  Further  details are given with
       pcre_exec() below.

	 PCRE_CONFIG_MATCH_LIMIT_RECURSION

       The output is a long integer that gives the default limit for the depth of recursion  when
       calling	the  internal  matching  function in a pcre_exec() execution. Further details are
       given with pcre_exec() below.

	 PCRE_CONFIG_STACKRECURSE

       The output is an integer that is set to one if internal recursion when running pcre_exec()
       is  implemented	by  recursive  function calls that use the stack to remember their state.
       This is the usual way that PCRE is compiled. The output is zero if PCRE	was  compiled  to
       use  blocks  of	data  on  the  heap  instead  of  recursive function calls. In this case,
       pcre_stack_malloc and pcre_stack_free are called to manage memory blocks on the heap, thus
       avoiding the use of the stack.

COMPILING A PATTERN

       pcre *pcre_compile(const char *pattern, int options,
	    const char **errptr, int *erroffset,
	    const unsigned char *tableptr);

       pcre *pcre_compile2(const char *pattern, int options,
	    int *errorcodeptr,
	    const char **errptr, int *erroffset,
	    const unsigned char *tableptr);

       Either  of the functions pcre_compile() or pcre_compile2() can be called to compile a pat-
       tern into an internal form. The	only  difference  between  the	two  interfaces  is  that
       pcre_compile2() has an additional argument, errorcodeptr, via which a numerical error code
       can be returned.

       The pattern is a C string terminated by a binary zero, and is passed in the pattern  argu-
       ment.  A pointer to a single block of memory that is obtained via pcre_malloc is returned.
       This contains the compiled code and related  data.  The	pcre  type  is	defined  for  the
       returned  block;  this  is  a  typedef  for  a structure whose contents are not externally
       defined. It is up to the caller to free the memory (via pcre_free) when it  is  no  longer
       required.

       Although  the compiled code of a PCRE regex is relocatable, that is, it does not depend on
       memory location, the complete pcre data block is not fully  relocatable,  because  it  may
       contain a copy of the tableptr argument, which is an address (see below).

       The  options argument contains various bit settings that affect the compilation. It should
       be zero if no options are required. The available options are  described  below.  Some  of
       them  (in  particular, those that are compatible with Perl, but also some others) can also
       be set and unset from within the pattern (see the detailed description in the  pcrepattern
       documentation). For those options that can be different in different parts of the pattern,
       the contents of the options argument specifies their initial settings at the start of com-
       pilation  and  execution. The PCRE_ANCHORED and PCRE_NEWLINE_xxx options can be set at the
       time of matching as well as at compile time.

       If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise, if compilation  of
       a  pattern  fails, pcre_compile() returns NULL, and sets the variable pointed to by errptr
       to point to a textual error message. This is a static string that is part of the  library.
       You  must  not  try  to free it. The offset from the start of the pattern to the character
       where the error was discovered is placed in the variable pointed to  by	erroffset,  which
       must not be NULL. If it is, an immediate error is given.

       If pcre_compile2() is used instead of pcre_compile(), and the errorcodeptr argument is not
       NULL, a non-zero error code number is returned via this argument in the event of an error.
       This  is  in  addition  to  the textual error message. Error codes and messages are listed
       below.

       If the final argument, tableptr, is NULL, PCRE uses a default set of character tables that
       are  built  when PCRE is compiled, using the default C locale. Otherwise, tableptr must be
       an address that is the result of a call to pcre_maketables(). This value  is  stored  with
       the  compiled  pattern,	and  used  again  by pcre_exec(), unless another table pointer is
       passed to it. For more discussion, see the section on locale support below.

       This code fragment shows a typical straightforward call to pcre_compile():

	 pcre *re;
	 const char *error;
	 int erroffset;
	 re = pcre_compile(
	   "^A.*Z",	     /* the pattern */
	   0,		     /* default options */
	   &error,	     /* for error message */
	   &erroffset,	     /* for error offset */
	   NULL);	     /* use default character tables */

       The following names for option bits are defined in the pcre.h header file:

	 PCRE_ANCHORED

       If this bit is set, the pattern is forced to be "anchored", that is, it is constrained  to
       match  only at the first matching point in the string that is being searched (the "subject
       string"). This effect can also be  achieved  by	appropriate  constructs  in  the  pattern
       itself, which is the only way to do it in Perl.

	 PCRE_AUTO_CALLOUT

       If  this  bit  is set, pcre_compile() automatically inserts callout items, all with number
       255, before each pattern item. For discussion of the callout facility, see the pcrecallout
       documentation.

	 PCRE_BSR_ANYCRLF
	 PCRE_BSR_UNICODE

       These  options (which are mutually exclusive) control what the \R escape sequence matches.
       The choice is either to match only CR, LF, or  CRLF,  or  to  match  any  Unicode  newline
       sequence.  The  default	is specified when PCRE is built. It can be overridden from within
       the pattern, or by setting an option when a compiled pattern is matched.

	 PCRE_CASELESS

       If this bit is set, letters in the pattern match both upper and lower case letters. It  is
       equivalent  to  Perl's  /i option, and it can be changed within a pattern by a (?i) option
       setting. In UTF-8 mode, PCRE always understands the concept of case for	characters  whose
       values  are  less  than	128, so caseless matching is always possible. For characters with
       higher values, the concept of case is supported if PCRE is compiled with Unicode  property
       support,  but  not  otherwise. If you want to use caseless matching for characters 128 and
       above, you must ensure that PCRE is compiled with Unicode property support as well as with
       UTF-8 support.

	 PCRE_DOLLAR_ENDONLY

       If  this  bit is set, a dollar metacharacter in the pattern matches only at the end of the
       subject string. Without this option, a dollar also matches immediately before a newline at
       the  end of the string (but not before any other newlines). The PCRE_DOLLAR_ENDONLY option
       is ignored if PCRE_MULTILINE is set.  There is no equivalent to this option in  Perl,  and
       no way to set it within a pattern.

	 PCRE_DOTALL

       If  this  bit  is set, a dot metacharater in the pattern matches all characters, including
       those that indicate newline. Without it, a dot does not match when the current position is
       at  a newline. This option is equivalent to Perl's /s option, and it can be changed within
       a pattern by a (?s) option setting. A negative class such as [^a] always  matches  newline
       characters, independent of the setting of this option.

	 PCRE_DUPNAMES

       If  this bit is set, names used to identify capturing subpatterns need not be unique. This
       can be helpful for certain types of pattern when it is known that only one instance of the
       named  subpattern  can ever be matched. There are more details of named subpatterns below;
       see also the pcrepattern documentation.

	 PCRE_EXTENDED

       If this bit is set, whitespace data characters in the pattern are totally  ignored  except
       when  escaped  or  inside  a character class. Whitespace does not include the VT character
       (code 11). In addition, characters between an unescaped # outside a  character  class  and
       the next newline, inclusive, are also ignored. This is equivalent to Perl's /x option, and
       it can be changed within a pattern by a (?x) option setting.

       This option makes it possible to include comments inside complicated patterns.  Note, how-
       ever,  that  this  applies only to data characters. Whitespace characters may never appear
       within special character sequences in a pattern, for example within the sequence (?( which
       introduces a conditional subpattern.

	 PCRE_EXTRA

       This  option  was  invented  in	order to turn on additional functionality of PCRE that is
       incompatible with Perl, but it is currently of very little use. When set, any backslash in
       a  pattern  that is followed by a letter that has no special meaning causes an error, thus
       reserving these combinations for future expansion. By default, as  in  Perl,  a	backslash
       followed  by a letter with no special meaning is treated as a literal. (Perl can, however,
       be persuaded to give a warning for this.) There are at  present	no  other  features  con-
       trolled by this option. It can also be set by a (?X) option setting within a pattern.

	 PCRE_FIRSTLINE

       If  this  option is set, an unanchored pattern is required to match before or at the first
       newline in the subject string, though the matched text may continue over the newline.

	 PCRE_JAVASCRIPT_COMPAT

       If this option is set, PCRE's behaviour is changed in some ways so that it  is  compatible
       with JavaScript rather than Perl. The changes are as follows:

       (1)  A  lone closing square bracket in a pattern causes a compile-time error, because this
       is illegal in JavaScript (by default it is treated as a data character). Thus, the pattern
       AB]CD becomes illegal when this option is set.

       (2) At run time, a back reference to an unset subpattern group matches an empty string (by
       default this causes the current matching alternative to fail). A pattern such  as  (\1)(a)
       succeeds  when this option is set (assuming it can find an "a" in the subject), whereas it
       fails by default, for Perl compatibility.

	 PCRE_MULTILINE

       By default, PCRE treats the subject string as consisting of a single  line  of  characters
       (even  if  it  actually	contains newlines). The "start of line" metacharacter (^) matches
       only at the start of the string, while the "end of line" metacharacter ($) matches only at
       the  end  of  the  string,  or before a terminating newline (unless PCRE_DOLLAR_ENDONLY is
       set). This is the same as Perl.

       When PCRE_MULTILINE it is set, the "start of line" and  "end  of  line"	constructs  match
       immediately  following  or  immediately	before	internal  newlines in the subject string,
       respectively, as well as at the very start and  end.  This  is  equivalent  to  Perl's  /m
       option,	and  it can be changed within a pattern by a (?m) option setting. If there are no
       newlines in a subject string, or no occurrences of ^ or $ in a pattern, setting	PCRE_MUL-
       TILINE has no effect.

	 PCRE_NEWLINE_CR
	 PCRE_NEWLINE_LF
	 PCRE_NEWLINE_CRLF
	 PCRE_NEWLINE_ANYCRLF
	 PCRE_NEWLINE_ANY

       These options override the default newline definition that was chosen when PCRE was built.
       Setting the first or the second specifies that a newline is indicated by a single  charac-
       ter  (CR or LF, respectively). Setting PCRE_NEWLINE_CRLF specifies that a newline is indi-
       cated by the two-character CRLF sequence. Setting PCRE_NEWLINE_ANYCRLF specifies that  any
       of  the three preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies
       that any Unicode newline sequence should be recognized. The Unicode newline sequences  are
       the  three just mentioned, plus the single characters VT (vertical tab, U+000B), FF (form-
       feed, U+000C), NEL (next line, U+0085), LS (line separator,  U+2028),  and  PS  (paragraph
       separator, U+2029). The last two are recognized only in UTF-8 mode.

       The newline setting in the options word uses three bits that are treated as a number, giv-
       ing eight possibilities. Currently only six are used (default plus the five values above).
       This means that if you set more than one newline option, the combination may or may not be
       sensible. For example, PCRE_NEWLINE_CR with PCRE_NEWLINE_LF  is	equivalent  to	PCRE_NEW-
       LINE_CRLF, but other combinations may yield unused numbers and cause an error.

       The  only  time	that  a line break is specially recognized when compiling a pattern is if
       PCRE_EXTENDED is set, and an unescaped # outside a character class  is  encountered.  This
       indicates  a comment that lasts until after the next line break sequence. In other circum-
       stances, line break sequences are treated as literal data, except  that	in  PCRE_EXTENDED
       mode, both CR and LF are treated as whitespace characters and are therefore ignored.

       The  newline  option  that  is  set  at	compile time becomes the default that is used for
       pcre_exec() and pcre_dfa_exec(), but it can be overridden.

	 PCRE_NO_AUTO_CAPTURE

       If this option is set, it disables the use of numbered capturing parentheses in	the  pat-
       tern.  Any opening parenthesis that is not followed by ? behaves as if it were followed by
       ?: but named parentheses can still be used for capturing (and they acquire numbers in  the
       usual way). There is no equivalent of this option in Perl.

	 PCRE_UNGREEDY

       This  option  inverts  the  "greediness" of the quantifiers so that they are not greedy by
       default, but become greedy if followed by "?". It is not compatible with Perl. It can also
       be set by a (?U) option setting within the pattern.

	 PCRE_UTF8

       This  option  causes  PCRE  to regard both the pattern and the subject as strings of UTF-8
       characters instead of single-byte character strings. However, it is  available  only  when
       PCRE  is built to include UTF-8 support. If not, the use of this option provokes an error.
       Details of how this option changes the behaviour of PCRE are given in the section on UTF-8
       support in the main pcre page.

	 PCRE_NO_UTF8_CHECK

       When  PCRE_UTF8	is  set,  the  validity of the pattern as a UTF-8 string is automatically
       checked. There is a discussion about the validity of UTF-8 strings in the main pcre  page.
       If  an  invalid	UTF-8 sequence of bytes is found, pcre_compile() returns an error. If you
       already know that your pattern is valid, and you want to skip this check  for  performance
       reasons,  you can set the PCRE_NO_UTF8_CHECK option. When it is set, the effect of passing
       an invalid UTF-8 string as a pattern is undefined. It may cause	your  program  to  crash.
       Note  that  this option can also be passed to pcre_exec() and pcre_dfa_exec(), to suppress
       the UTF-8 validity checking of subject strings.

COMPILATION ERROR CODES

       The following table lists the error codes than may be returned by  pcre_compile2(),  along
       with  the  error  messages  that  may be returned by both compiling functions. As PCRE has
       developed, some error codes have fallen out of use. To avoid confusion, they have not been
       re-used.

	  0  no error
	  1  \ at end of pattern
	  2  \c at end of pattern
	  3  unrecognized character follows \
	  4  numbers out of order in {} quantifier
	  5  number too big in {} quantifier
	  6  missing terminating ] for character class
	  7  invalid escape sequence in character class
	  8  range out of order in character class
	  9  nothing to repeat
	 10  [this code is not in use]
	 11  internal error: unexpected repeat
	 12  unrecognized character after (? or (?-
	 13  POSIX named classes are supported only within a class
	 14  missing )
	 15  reference to non-existent subpattern
	 16  erroffset passed as NULL
	 17  unknown option bit(s) set
	 18  missing ) after comment
	 19  [this code is not in use]
	 20  regular expression is too large
	 21  failed to get memory
	 22  unmatched parentheses
	 23  internal error: code overflow
	 24  unrecognized character after (?<
	 25  lookbehind assertion is not fixed length
	 26  malformed number or name after (?(
	 27  conditional group contains more than two branches
	 28  assertion expected after (?(
	 29  (?R or (?[+-]digits must be followed by )
	 30  unknown POSIX class name
	 31  POSIX collating elements are not supported
	 32  this version of PCRE is not compiled with PCRE_UTF8 support
	 33  [this code is not in use]
	 34  character value in \x{...} sequence is too large
	 35  invalid condition (?(0)
	 36  \C not allowed in lookbehind assertion
	 37  PCRE does not support \L, \l, \N, \U, or \u
	 38  number after (?C is > 255
	 39  closing ) for (?C expected
	 40  recursive call could loop indefinitely
	 41  unrecognized character after (?P
	 42  syntax error in subpattern name (missing terminator)
	 43  two named subpatterns have the same name
	 44  invalid UTF-8 string
	 45  support for \P, \p, and \X has not been compiled
	 46  malformed \P or \p sequence
	 47  unknown property name after \P or \p
	 48  subpattern name is too long (maximum 32 characters)
	 49  too many named subpatterns (maximum 10000)
	 50  [this code is not in use]
	 51  octal value is greater than \377 (not in UTF-8 mode)
	 52  internal error: overran compiling workspace
	 53  internal error: previously-checked referenced subpattern not found
	 54  DEFINE group contains more than one branch
	 55  repeating a DEFINE group is not allowed
	 56  inconsistent NEWLINE options
	 57  \g is not followed by a braced, angle-bracketed, or quoted
	       name/number or by a plain number
	 58  a numbered reference must not be zero
	 59  (*VERB) with an argument is not supported
	 60  (*VERB) not recognized
	 61  number is too big
	 62  subpattern name expected
	 63  digit expected after (?+
	 64  ] is an invalid data character in JavaScript compatibility mode

       The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may be used if
       the limits were changed when PCRE was built.

STUDYING A PATTERN

       pcre_extra *pcre_study(const pcre *code, int options
	    const char **errptr);

       If a compiled pattern is going to be used several times, it is worth  spending  more  time
       analyzing  it  in order to speed up the time taken for matching. The function pcre_study()
       takes a pointer to a compiled pattern as its first argument. If studying the pattern  pro-
       duces  additional  information  that  will  help speed up matching, pcre_study() returns a
       pointer to a pcre_extra block, in which the study_data field points to the results of  the
       study.

       The  returned  value  from  pcre_study() can be passed directly to pcre_exec(). However, a
       pcre_extra block also contains other fields that can be set by the caller before the block
       is passed; these are described below in the section on matching a pattern.

       If  studying  the pattern does not produce any additional information pcre_study() returns
       NULL. In that circumstance, if the calling program wants to pass any of the  other  fields
       to pcre_exec(), it must set up its own pcre_extra block.

       The  second  argument  of  pcre_study()	contains  option bits. At present, no options are
       defined, and this argument should always be zero.

       The third argument for pcre_study() is a pointer for an error message.  If  studying  suc-
       ceeds  (even  if no data is returned), the variable it points to is set to NULL. Otherwise
       it is set to point to a textual error message. This is a static string that is part of the
       library.  You  must  not  try to free it. You should test the error pointer for NULL after
       calling pcre_study(), to be sure that it has run successfully.

       This is a typical call to pcre_study():

	 pcre_extra *pe;
	 pe = pcre_study(
	   re,		   /* result of pcre_compile() */
	   0,		   /* no options exist */
	   &error);	   /* set to NULL or points to a message */

       At present, studying a pattern is useful only for non-anchored patterns that do not have a
       single fixed starting character. A bitmap of possible starting bytes is created.

LOCALE SUPPORT

       PCRE  handles caseless matching, and determines whether characters are letters, digits, or
       whatever, by reference to a set of tables, indexed by character	value.	When  running  in
       UTF-8  mode, this applies only to characters with codes less than 128. Higher-valued codes
       never match escapes such as \w or \d, but can be tested with \p if PCRE is built with Uni-
       code  character	property  support. The use of locales with Unicode is discouraged. If you
       are handling characters with codes greater than 128, you should either use UTF-8 and  Uni-
       code, or use locales, but not try to mix the two.

       PCRE contains an internal set of tables that are used when the final argument of pcre_com-
       pile() is NULL. These are sufficient for many applications.  Normally, the internal tables
       recognize  only ASCII characters. However, when PCRE is built, it is possible to cause the
       internal tables to be rebuilt in the default "C" locale of the  local  system,  which  may
       cause them to be different.

       The  internal  tables  can always be overridden by tables supplied by the application that
       calls PCRE. These may be created in a different locale from the default. As more and  more
       applications  change to using Unicode, the need for this locale support is expected to die
       away.

       External tables are built by calling the pcre_maketables() function, which  has	no  argu-
       ments,  in  the	relevant  locale.  The	result	can  then  be passed to pcre_compile() or
       pcre_exec() as often as necessary. For example, to build and use tables that are appropri-
       ate  for  the  French  locale  (where accented characters with values greater than 128 are
       treated as letters), the following code could be used:

	 setlocale(LC_CTYPE, "fr_FR");
	 tables = pcre_maketables();
	 re = pcre_compile(..., tables);

       The locale name "fr_FR" is used on Linux and other Unix-like systems;  if  you  are  using
       Windows, the name for the French locale is "french".

       When pcre_maketables() runs, the tables are built in memory that is obtained via pcre_mal-
       loc. It is the caller's responsibility to ensure that the  memory  containing  the  tables
       remains available for as long as it is needed.

       The  pointer  that is passed to pcre_compile() is saved with the compiled pattern, and the
       same tables are used via this pointer by pcre_study() and normally  also  by  pcre_exec().
       Thus, by default, for any single pattern, compilation, studying and matching all happen in
       the same locale, but different patterns can be compiled in different locales.

       It is possible to pass a table pointer or NULL (indicating the use of the internal tables)
       to  pcre_exec().  Although  not	intended for this purpose, this facility could be used to
       match a pattern in a different locale from the one in which it was compiled. Passing table
       pointers at run time is discussed below in the section on matching a pattern.

INFORMATION ABOUT A PATTERN

       int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
	    int what, void *where);

       The pcre_fullinfo() function returns information about a compiled pattern. It replaces the
       obsolete pcre_info() function, which is nevertheless retained  for  backwards  compability
       (and is documented below).

       The  first  argument  for pcre_fullinfo() is a pointer to the compiled pattern. The second
       argument is the result of pcre_study(), or NULL if the pattern was not studied. The  third
       argument  specifies  which  piece of information is required, and the fourth argument is a
       pointer to a variable to receive the data. The yield of the function is zero for  success,
       or one of the following negative numbers:

	 PCRE_ERROR_NULL       the argument code was NULL
			       the argument where was NULL
	 PCRE_ERROR_BADMAGIC   the "magic number" was not found
	 PCRE_ERROR_BADOPTION  the value of what was invalid

       The  "magic  number"  is  placed  at the start of each compiled pattern as an simple check
       against passing an arbitrary memory pointer. Here is a typical call of pcre_fullinfo(), to
       obtain the length of the compiled pattern:

	 int rc;
	 size_t length;
	 rc = pcre_fullinfo(
	   re,		     /* result of pcre_compile() */
	   pe,		     /* result of pcre_study(), or NULL */
	   PCRE_INFO_SIZE,   /* what is required */
	   &length);	     /* where to put the data */

       The possible values for the third argument are defined in pcre.h, and are as follows:

	 PCRE_INFO_BACKREFMAX

       Return the number of the highest back reference in the pattern. The fourth argument should
       point to an int variable. Zero is returned if there are no back references.

	 PCRE_INFO_CAPTURECOUNT

       Return the number of capturing subpatterns in the  pattern.  The  fourth  argument  should
       point to an int variable.

	 PCRE_INFO_DEFAULT_TABLES

       Return a pointer to the internal default character tables within PCRE. The fourth argument
       should point to an unsigned char * variable. This information call is provided for  inter-
       nal  use by the pcre_study() function. External callers can cause PCRE to use its internal
       tables by passing a NULL table pointer.

	 PCRE_INFO_FIRSTBYTE

       Return information about the first byte of any matched string, for a non-anchored pattern.
       The  fourth  argument  should  point  to  an  int variable. (This option used to be called
       PCRE_INFO_FIRSTCHAR; the old name is still recognized for backwards compatibility.)

       If there is a fixed first byte, for example, from a pattern such as (cat|cow|coyote),  its
       value is returned. Otherwise, if either

       (a)  the pattern was compiled with the PCRE_MULTILINE option, and every branch starts with
       "^", or

       (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set  (if  it  were
       set, the pattern would be anchored),

       -1  is returned, indicating that the pattern matches only at the start of a subject string
       or after any newline within the string. Otherwise -2 is returned. For  anchored	patterns,
       -2 is returned.

	 PCRE_INFO_FIRSTTABLE

       If the pattern was studied, and this resulted in the construction of a 256-bit table indi-
       cating a fixed set of bytes for the first byte in any matching string, a  pointer  to  the
       table  is  returned.  Otherwise	NULL  is returned. The fourth argument should point to an
       unsigned char * variable.

	 PCRE_INFO_HASCRORLF

       Return 1 if the pattern contains any explicit matches for CR or LF  characters,	otherwise
       0. The fourth argument should point to an int variable. An explicit match is either a lit-
       eral CR or LF character, or \r or \n.

	 PCRE_INFO_JCHANGED

       Return 1 if the (?J) or (?-J) option setting is used in	the  pattern,  otherwise  0.  The
       fourth  argument  should  point to an int variable. (?J) and (?-J) set and unset the local
       PCRE_DUPNAMES option, respectively.

	 PCRE_INFO_LASTLITERAL

       Return the value of the rightmost literal byte that must  exist	in  any  matched  string,
       other  than  at	its  start,  if such a byte has been recorded. The fourth argument should
       point to an int variable. If there is no such byte, -1 is returned. For anchored patterns,
       a last literal byte is recorded only if it follows something of variable length. For exam-
       ple, for the pattern /^a\d+z\d+/ the returned value is "z", but for /^a\dz\d/ the returned
       value is -1.

	 PCRE_INFO_NAMECOUNT
	 PCRE_INFO_NAMEENTRYSIZE
	 PCRE_INFO_NAMETABLE

       PCRE  supports  the  use of named as well as numbered capturing parentheses. The names are
       just an additional way of identifying the parentheses, which still acquire  numbers.  Sev-
       eral  convenience functions such as pcre_get_named_substring() are provided for extracting
       captured substrings by name. It is also possible to extract the data  directly,	by  first
       converting the name to a number in order to access the correct pointers in the output vec-
       tor (described with pcre_exec() below). To do the conversion, you need to use the name-to-
       number map, which is described by these three values.

       The  map  consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT gives the number
       of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size of each entry; both of these return
       an   int   value.   The	 entry	 size	depends  on  the  length  of  the  longest  name.
       PCRE_INFO_NAMETABLE returns a pointer to the first entry of the table (a pointer to char).
       The  first  two bytes of each entry are the number of the capturing parenthesis, most sig-
       nificant byte first. The rest of the entry is the corresponding name, zero terminated. The
       names  are  in alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order
       of their  parentheses  numbers.	For  example,  consider  the  following  pattern  (assume
       PCRE_EXTENDED is set, so white space - including newlines - is ignored):

	 (?<date> (?<year>(\d\d)?\d\d) -
	 (?<month>\d\d) - (?<day>\d\d) )

       There are four named subpatterns, so the table has four entries, and each entry in the ta-
       ble is eight bytes long. The table is as follows, with non-printing bytes shows	in  hexa-
       decimal, and undefined bytes shown as ??:

	 00 01 d  a  t	e  00 ??
	 00 05 d  a  y	00 ?? ??
	 00 04 m  o  n	t  h  00
	 00 02 y  e  a	r  00 ??

       When  writing  code  to	extract data from named subpatterns using the name-to-number map,
       remember that the length of the entries is likely to be different for each  compiled  pat-
       tern.

	 PCRE_INFO_OKPARTIAL

       Return 1 if the pattern can be used for partial matching, otherwise 0. The fourth argument
       should point to an int variable. The pcrepartial documentation lists the restrictions that
       apply to patterns when partial matching is used.

	 PCRE_INFO_OPTIONS

       Return  a  copy	of  the  options with which the pattern was compiled. The fourth argument
       should point to an unsigned long int variable. These option bits are  those  specified  in
       the  call to pcre_compile(), modified by any top-level option settings at the start of the
       pattern itself. In other words, they are the options that will be in force  when  matching
       starts.	For  example,  if the pattern /(?im)abc(?-i)d/ is compiled with the PCRE_EXTENDED
       option, the result is PCRE_CASELESS, PCRE_MULTILINE, and PCRE_EXTENDED.

       A pattern is automatically anchored by PCRE if all of  its  top-level  alternatives  begin
       with one of the following:

	 ^     unless PCRE_MULTILINE is set
	 \A    always
	 \G    always
	 .*    if PCRE_DOTALL is set and there are no back
		 references to the subpattern in which .* appears

       For   such   patterns,	the   PCRE_ANCHORED  bit  is  set  in  the  options  returned  by
       pcre_fullinfo().

	 PCRE_INFO_SIZE

       Return the size of the compiled pattern, that is, the value that was passed as  the  argu-
       ment  to  pcre_malloc()	when PCRE was getting memory in which to place the compiled data.
       The fourth argument should point to a size_t variable.

	 PCRE_INFO_STUDYSIZE

       Return the size of the data block pointed to by	the  study_data  field	in  a  pcre_extra
       block.  That  is,  it  is the value that was passed to pcre_malloc() when PCRE was getting
       memory into which to place the data created by pcre_study(). The  fourth  argument  should
       point to a size_t variable.

OBSOLETE INFO FUNCTION

       int pcre_info(const pcre *code, int *optptr, int *firstcharptr);

       The  pcre_info()  function  is  now  obsolete  because its interface is too restrictive to
       return all  the	available  data  about	a  compiled  pattern.  New  programs  should  use
       pcre_fullinfo()	instead. The yield of pcre_info() is the number of capturing subpatterns,
       or one of the following negative numbers:

	 PCRE_ERROR_NULL       the argument code was NULL
	 PCRE_ERROR_BADMAGIC   the "magic number" was not found

       If the optptr argument is not NULL, a copy of the options with which the pattern was  com-
       piled is placed in the integer it points to (see PCRE_INFO_OPTIONS above).

       If  the	pattern  is not anchored and the firstcharptr argument is not NULL, it is used to
       pass  back  information	about  the  first  character   of   any   matched   string   (see
       PCRE_INFO_FIRSTBYTE above).

REFERENCE COUNTS

       int pcre_refcount(pcre *code, int adjust);

       The  pcre_refcount() function is used to maintain a reference count in the data block that
       contains a compiled pattern. It is provided for the benefit of applications  that  operate
       in  an  object-oriented	manner, where different parts of the application may be using the
       same compiled pattern, but you want to free the block when they are all done.

       When a pattern is compiled, the reference count field  is  initialized  to  zero.   It  is
       changed	only by calling this function, whose action is to add the adjust value (which may
       be positive or negative) to it. The yield of the function is the new value.  However,  the
       value  of the count is constrained to lie between 0 and 65535, inclusive. If the new value
       is outside these limits, it is forced to the appropriate limit value.

       Except when it is zero, the reference count is not correctly preserved  if  a  pattern  is
       compiled  on  one host and then transferred to a host whose byte-order is different. (This
       seems a highly unlikely scenario.)

MATCHING A PATTERN: THE TRADITIONAL FUNCTION

       int pcre_exec(const pcre *code, const pcre_extra *extra,
	    const char *subject, int length, int startoffset,
	    int options, int *ovector, int ovecsize);

       The function pcre_exec() is called to match a subject string against a  compiled  pattern,
       which  is  passed in the code argument. If the pattern has been studied, the result of the
       study should be passed in the extra argument. This function is the main matching  facility
       of the library, and it operates in a Perl-like manner. For specialist use there is also an
       alternative matching  function,	which  is  described  below  in  the  section  about  the
       pcre_dfa_exec() function.

       In  most applications, the pattern will have been compiled (and optionally studied) in the
       same process that calls pcre_exec(). However, it is possible to save compiled patterns and
       study  data,  and  then	use them later in different processes, possibly even on different
       hosts. For a discussion about this, see the pcreprecompile documentation.

       Here is an example of a simple call to pcre_exec():

	 int rc;
	 int ovector[30];
	 rc = pcre_exec(
	   re,		   /* result of pcre_compile() */
	   NULL,	   /* we didn't study the pattern */
	   "some string",  /* the subject string */
	   11,		   /* the length of the subject string */
	   0,		   /* start at offset 0 in the subject */
	   0,		   /* default options */
	   ovector,	   /* vector of integers for substring information */
	   30); 	   /* number of elements (NOT size in bytes) */

   Extra data for pcre_exec()

       If the extra argument is not  NULL,  it	must  point  to  a  pcre_extra	data  block.  The
       pcre_study() function returns such a block (when it doesn't return NULL), but you can also
       create one for yourself, and pass additional information in it. The pcre_extra block  con-
       tains the following fields (not necessarily in this order):

	 unsigned long int flags;
	 void *study_data;
	 unsigned long int match_limit;
	 unsigned long int match_limit_recursion;
	 void *callout_data;
	 const unsigned char *tables;

       The  flags  field  is  a bitmap that specifies which of the other fields are set. The flag
       bits are:

	 PCRE_EXTRA_STUDY_DATA
	 PCRE_EXTRA_MATCH_LIMIT
	 PCRE_EXTRA_MATCH_LIMIT_RECURSION
	 PCRE_EXTRA_CALLOUT_DATA
	 PCRE_EXTRA_TABLES

       Other flag bits should be set to zero. The study_data field is set in the pcre_extra block
       that  is  returned by pcre_study(), together with the appropriate flag bit. You should not
       set this yourself, but you may add to the block by setting the other fields and their cor-
       responding flag bits.

       The  match_limit  field provides a means of preventing PCRE from using up a vast amount of
       resources when running patterns that are not going to match, but which have a  very  large
       number  of  possibilities  in their search trees. The classic example is the use of nested
       unlimited repeats.

       Internally, PCRE uses a function called	match()  which	it  calls  repeatedly  (sometimes
       recursively). The limit set by match_limit is imposed on the number of times this function
       is called during a match, which has the effect of limiting the amount of backtracking that
       can  take place. For patterns that are not anchored, the count restarts from zero for each
       position in the subject string.

       The default value for the limit can be set when PCRE is built; the default default  is  10
       million,  which	handles  all  but the most extreme cases. You can override the default by
       suppling  pcre_exec()  with  a  pcre_extra  block  in  which  match_limit  is   set,   and
       PCRE_EXTRA_MATCH_LIMIT  is  set	in the flags field. If the limit is exceeded, pcre_exec()
       returns PCRE_ERROR_MATCHLIMIT.

       The match_limit_recursion field is similar to match_limit, but  instead	of  limiting  the
       total number of times that match() is called, it limits the depth of recursion. The recur-
       sion depth is a smaller number than the total number of calls, because not  all	calls  to
       match() are recursive.  This limit is of use only if it is set smaller than match_limit.

       Limiting  the  recursion  depth limits the amount of stack that can be used, or, when PCRE
       has been compiled to use memory on the heap instead of the stack, the amount of heap  mem-
       ory that can be used.

       The  default  value  for  match_limit_recursion can be set when PCRE is built; the default
       default is the same value as the default for match_limit. You can override the default  by
       suppling  pcre_exec()  with  a pcre_extra block in which match_limit_recursion is set, and
       PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the flags field.  If	the  limit  is	exceeded,
       pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.

       The  pcre_callout  field  is  used  in  conjunction  with  the "callout" feature, which is
       described in the pcrecallout documentation.

       The tables field is used to pass a character tables pointer to pcre_exec(); this overrides
       the  value  that  is stored with the compiled pattern. A non-NULL value is stored with the
       compiled pattern only if custom tables were supplied to pcre_compile()  via  its  tableptr
       argument.   If NULL is passed to pcre_exec() using this mechanism, it forces PCRE's inter-
       nal tables to be used. This facility is helpful when  re-using  patterns  that  have  been
       saved after compiling with an external set of tables, because the external tables might be
       at a different address when pcre_exec() is called. See  the  pcreprecompile  documentation
       for a discussion of saving compiled patterns for later use.

   Option bits for pcre_exec()

       The  unused  bits of the options argument for pcre_exec() must be zero. The only bits that
       may be set are PCRE_ANCHORED, PCRE_NEWLINE_xxx, PCRE_NOTBOL,  PCRE_NOTEOL,  PCRE_NOTEMPTY,
       PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.

	 PCRE_ANCHORED

       The PCRE_ANCHORED option limits pcre_exec() to matching at the first matching position. If
       a pattern was compiled with PCRE_ANCHORED, or turned out to be anchored by virtue  of  its
       contents, it cannot be made unachored at matching time.

	 PCRE_BSR_ANYCRLF
	 PCRE_BSR_UNICODE

       These  options (which are mutually exclusive) control what the \R escape sequence matches.
       The choice is either to match only CR, LF, or  CRLF,  or  to  match  any  Unicode  newline
       sequence.  These  options  override the choice that was made or defaulted when the pattern
       was compiled.

	 PCRE_NEWLINE_CR
	 PCRE_NEWLINE_LF
	 PCRE_NEWLINE_CRLF
	 PCRE_NEWLINE_ANYCRLF
	 PCRE_NEWLINE_ANY

       These options override the newline definition that was chosen or defaulted when	the  pat-
       tern was compiled. For details, see the description of pcre_compile() above. During match-
       ing, the newline choice affects the behaviour of the dot, circumflex, and dollar metachar-
       acters. It may also alter the way the match position is advanced after a match failure for
       an unanchored pattern.

       When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY  is  set,  and  a  match
       attempt	for  an unanchored pattern fails when the current position is at a CRLF sequence,
       and the pattern contains no explicit matches for CR or LF characters, the  match  position
       is advanced by two characters instead of one, in other words, to after the CRLF.

       The  above  rule  is  a	compromise that makes the most common cases work as expected. For
       example, if the pattern is .+A (and the PCRE_DOTALL option is not set), it does not  match
       the  string  "\r\nA"  because, after failing at the start, it skips both the CR and the LF
       before retrying. However, the pattern [\r\n]A does match that string, because it  contains
       an  explicit  CR  or  LF  reference, and so advances only by one character after the first
       failure.

       An explicit match for CR of LF is either a literal appearance of one of those  characters,
       or  one	of the \r or \n escape sequences. Implicit matches such as [^X] do not count, nor
       does \s (which includes CR and LF in the characters that it matches).

       Notwithstanding the above, anomalous effects may still occur when CRLF is a valid  newline
       sequence and explicit \r or \n escapes appear in the pattern.

	 PCRE_NOTBOL

       This option specifies that first character of the subject string is not the beginning of a
       line, so the circumflex metacharacter should not match before  it.  Setting  this  without
       PCRE_MULTILINE  (at  compile  time)  causes circumflex never to match. This option affects
       only the behaviour of the circumflex metacharacter. It does not affect \A.

	 PCRE_NOTEOL

       This option specifies that the end of the subject string is not the end of a line, so  the
       dollar  metacharacter should not match it nor (except in multiline mode) a newline immedi-
       ately before it. Setting this without PCRE_MULTILINE (at compile time) causes dollar never
       to  match. This option affects only the behaviour of the dollar metacharacter. It does not
       affect \Z or \z.

	 PCRE_NOTEMPTY

       An empty string is not considered to be a valid match if this option is set. If there  are
       alternatives  in  the  pattern,	they  are  tried. If all the alternatives match the empty
       string, the entire match fails. For example, if the pattern

	 a?b?

       is applied to a string not beginning with "a" or "b", it matches the empty string  at  the
       start  of  the  subject. With PCRE_NOTEMPTY set, this match is not valid, so PCRE searches
       further into the string for occurrences of "a" or "b".

       Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case of a  pat-
       tern  match  of	the empty string within its split() function, and when using the /g modi-
       fier. It is possible to emulate Perl's behaviour after matching a  null	string	by  first
       trying  the  match again at the same offset with PCRE_NOTEMPTY and PCRE_ANCHORED, and then
       if that fails by advancing the starting offset (see below) and trying  an  ordinary  match
       again.  There  is some code that demonstrates how to do this in the pcredemo.c sample pro-
       gram.

	 PCRE_NO_START_OPTIMIZE

       There are a number of optimizations that pcre_exec() uses at the  start	of  a  match,  in
       order  to speed up the process. For example, if it is known that a match must start with a
       specific character, it searches the subject for that character, and fails  immediately  if
       it  cannot find it, without actually running the main matching function. When callouts are
       in use, these optimizations can cause them to be skipped. This option disables the "start-
       up" optimizations, causing performance to suffer, but ensuring that the callouts do occur.

	 PCRE_NO_UTF8_CHECK

       When  PCRE_UTF8	is  set at compile time, the validity of the subject as a UTF-8 string is
       automatically checked when pcre_exec() is subsequently called.  The value  of  startoffset
       is  also  checked  to  ensure that it points to the start of a UTF-8 character. There is a
       discussion about the validity of UTF-8 strings in the section on UTF-8 support in the main
       pcre  page.  If an invalid UTF-8 sequence of bytes is found, pcre_exec() returns the error
       PCRE_ERROR_BADUTF8. If startoffset contains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is
       returned.

       If you already know that your subject is valid, and you want to skip these checks for per-
       formance reasons, you can set the PCRE_NO_UTF8_CHECK option when calling pcre_exec().  You
       might want to do this for the second and subsequent calls to pcre_exec() if you are making
       repeated calls to find all the matches in a single subject string. However, you should  be
       sure  that  the	value  of  startoffset	points	to  the  start of a UTF-8 character. When
       PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid UTF-8 string as a subject,  or
       a  value  of  startoffset  that does not point to the start of a UTF-8 character, is unde-
       fined. Your program may crash.

	 PCRE_PARTIAL

       This option turns on the partial matching feature. If the subject string  fails	to  match
       the  pattern,  but  at  some  point during the matching process the end of the subject was
       reached (that is, the subject partially matches the  pattern  and  the  failure	to  match
       occurred  only  because	there  were  not  enough subject characters), pcre_exec() returns
       PCRE_ERROR_PARTIAL instead of PCRE_ERROR_NOMATCH. When PCRE_PARTIAL  is	used,  there  are
       restrictions  on  what  may  appear in the pattern. These are discussed in the pcrepartial
       documentation.

   The string to be matched by pcre_exec()

       The subject string is passed to pcre_exec() as a pointer in subject, a length  (in  bytes)
       in  length, and a starting byte offset in startoffset. In UTF-8 mode, the byte offset must
       point to the start of a UTF-8 character. Unlike the pattern string, the subject	may  con-
       tain binary zero bytes. When the starting offset is zero, the search for a match starts at
       the beginning of the subject, and this is by far the most common case.

       A non-zero starting offset is useful when searching for another match in the same  subject
       by  calling  pcre_exec() again after a previous success.  Setting startoffset differs from
       just passing over a shortened string and setting PCRE_NOTBOL in the case of a pattern that
       begins with any kind of lookbehind. For example, consider the pattern

	 \Biss\B

       which  finds  occurrences of "iss" in the middle of words. (\B matches only if the current
       position in the subject is not a word boundary.) When applied to the  string  "Mississipi"
       the  first  call to pcre_exec() finds the first occurrence. If pcre_exec() is called again
       with just the remainder of the subject, namely "issipi", it does not match, because \B  is
       always  false at the start of the subject, which is deemed to be a word boundary. However,
       if pcre_exec() is passed the entire string again, but with startoffset set to 4, it  finds
       the  second  occurrence	of  "iss" because it is able to look behind the starting point to
       discover that it is preceded by a letter.

       If a non-zero starting offset is passed when the pattern is anchored, one attempt to match
       at  the	given  offset  is made. This can only succeed if the pattern does not require the
       match to be at the start of the subject.

   How pcre_exec() returns captured substrings

       In general, a pattern matches a certain portion of the subject, and in  addition,  further
       substrings from the subject may be picked out by parts of the pattern. Following the usage
       in Jeffrey Friedl's book, this is called "capturing" in what follows, and the phrase "cap-
       turing  subpattern"  is	used for a fragment of a pattern that picks out a substring. PCRE
       supports several other kinds of parenthesized subpattern that do not cause  substrings  to
       be captured.

       Captured  substrings  are returned to the caller via a vector of integers whose address is
       passed in ovector. The number of elements in the vector is passed in ovecsize, which  must
       be a non-negative number. Note: this argument is NOT the size of ovector in bytes.

       The  first  two-thirds  of  the vector is used to pass back captured substrings, each sub-
       string using a pair of integers. The remaining third of the vector is used as workspace by
       pcre_exec()  while  matching  capturing subpatterns, and is not available for passing back
       information. The number passed in ovecsize should always be a multiple of three. If it  is
       not, it is rounded down.

       When  a match is successful, information about captured substrings is returned in pairs of
       integers, starting at the beginning of ovector, and continuing up  to  two-thirds  of  its
       length  at the most. The first element of each pair is set to the byte offset of the first
       character in a substring, and the second is set to the byte offset of the first	character
       after  the  end	of a substring. Note: these values are always byte offsets, even in UTF-8
       mode. They are not character counts.

       The first pair of integers, ovector[0] and ovector[1], identify the portion of the subject
       string  matched	by the entire pattern. The next pair is used for the first capturing sub-
       pattern, and so on. The value returned by pcre_exec() is one more than  the  highest  num-
       bered  pair  that  has  been  set.  For example, if two substrings have been captured, the
       returned value is 3. If there are no capturing subpatterns, the return value from  a  suc-
       cessful match is 1, indicating that just the first pair of offsets has been set.

       If a capturing subpattern is matched repeatedly, it is the last portion of the string that
       it matched that is returned.

       If the vector is too small to hold all the captured substring offsets, it is used  as  far
       as possible (up to two-thirds of its length), and the function returns a value of zero. If
       the substring offsets are not of interest, pcre_exec() may be called with  ovector  passed
       as  NULL  and  ovecsize	as zero. However, if the pattern contains back references and the
       ovector is not big enough to remember the related substrings, PCRE has to  get  additional
       memory for use during matching. Thus it is usually advisable to supply an ovector.

       The  pcre_info() function can be used to find out how many capturing subpatterns there are
       in a compiled pattern. The smallest size for ovector that will allow for n  captured  sub-
       strings,  in  addition  to  the	offsets of the substring matched by the whole pattern, is
       (n+1)*3.

       It is possible for capturing subpattern number n+1 to match some part of the subject  when
       subpattern n has not been used at all. For example, if the string "abc" is matched against
       the pattern (a|(z))(bc) the return from the function is 4, and subpatterns  1  and  3  are
       matched, but 2 is not. When this happens, both values in the offset pairs corresponding to
       unused subpatterns are set to -1.

       Offset values that correspond to unused subpatterns at the end of the expression are  also
       set  to -1. For example, if the string "abc" is matched against the pattern (abc)(x(yz)?)?
       subpatterns 2 and 3 are not matched. The return from the function is 2, because the  high-
       est  used  capturing subpattern number is 1. However, you can refer to the offsets for the
       second and third capturing subpatterns if you wish (assuming the vector is  large  enough,
       of course).

       Some convenience functions are provided for extracting the captured substrings as separate
       strings. These are described below.

   Error return values from pcre_exec()

       If pcre_exec() fails, it returns a negative number.  The  following  are  defined  in  the
       header file:

	 PCRE_ERROR_NOMATCH	   (-1)

       The subject string did not match the pattern.

	 PCRE_ERROR_NULL	   (-2)

       Either code or subject was passed as NULL, or ovector was NULL and ovecsize was not zero.

	 PCRE_ERROR_BADOPTION	   (-3)

       An unrecognized bit was set in the options argument.

	 PCRE_ERROR_BADMAGIC	   (-4)

       PCRE  stores  a 4-byte "magic number" at the start of the compiled code, to catch the case
       when it is passed a junk pointer and to detect when a pattern  that  was  compiled  in  an
       environment  of one endianness is run in an environment with the other endianness. This is
       the error that PCRE gives when the magic number is not present.

	 PCRE_ERROR_UNKNOWN_OPCODE (-5)

       While running the pattern match, an unknown item was encountered in the compiled  pattern.
       This error could be caused by a bug in PCRE or by overwriting of the compiled pattern.

	 PCRE_ERROR_NOMEMORY	   (-6)

       If  a  pattern  contains back references, but the ovector that is passed to pcre_exec() is
       not big enough to remember the referenced substrings, PCRE gets a block of memory  at  the
       start of matching to use for this purpose. If the call via pcre_malloc() fails, this error
       is given. The memory is automatically freed at the end of matching.

	 PCRE_ERROR_NOSUBSTRING    (-7)

       This error is used by the pcre_copy_substring(), pcre_get_substring(),  and  pcre_get_sub-
       string_list() functions (see below). It is never returned by pcre_exec().

	 PCRE_ERROR_MATCHLIMIT	   (-8)

       The  backtracking  limit,  as specified by the match_limit field in a pcre_extra structure
       (or defaulted) was reached. See the description above.

	 PCRE_ERROR_CALLOUT	   (-9)

       This error is never generated by pcre_exec() itself. It is provided  for  use  by  callout
       functions  that	want to yield a distinctive error code. See the pcrecallout documentation
       for details.

	 PCRE_ERROR_BADUTF8	   (-10)

       A string that contains an invalid UTF-8 byte sequence was passed as a subject.

	 PCRE_ERROR_BADUTF8_OFFSET (-11)

       The UTF-8 byte sequence that was passed as a subject was valid, but the value of startoff-
       set did not point to the beginning of a UTF-8 character.

	 PCRE_ERROR_PARTIAL	   (-12)

       The subject string did not match, but it did match partially. See the pcrepartial documen-
       tation for details of partial matching.

	 PCRE_ERROR_BADPARTIAL	   (-13)

       The PCRE_PARTIAL option was used with a compiled pattern containing  items  that  are  not
       supported  for  partial matching. See the pcrepartial documentation for details of partial
       matching.

	 PCRE_ERROR_INTERNAL	   (-14)

       An unexpected internal error has occurred. This error could be caused by a bug in PCRE  or
       by overwriting of the compiled pattern.

	 PCRE_ERROR_BADCOUNT	   (-15)

       This error is given if the value of the ovecsize argument is negative.

	 PCRE_ERROR_RECURSIONLIMIT (-21)

       The  internal  recursion  limit,  as  specified	by  the  match_limit_recursion field in a
       pcre_extra structure (or defaulted) was reached. See the description above.

	 PCRE_ERROR_BADNEWLINE	   (-23)

       An invalid combination of PCRE_NEWLINE_xxx options was given.

       Error numbers -16 to -20 and -22 are not used by pcre_exec().

EXTRACTING CAPTURED SUBSTRINGS BY NUMBER

       int pcre_copy_substring(const char *subject, int *ovector,
	    int stringcount, int stringnumber, char *buffer,
	    int buffersize);

       int pcre_get_substring(const char *subject, int *ovector,
	    int stringcount, int stringnumber,
	    const char **stringptr);

       int pcre_get_substring_list(const char *subject,
	    int *ovector, int stringcount, const char ***listptr);

       Captured substrings can be accessed directly by using the offsets returned by  pcre_exec()
       in  ovector.  For  convenience, the functions pcre_copy_substring(), pcre_get_substring(),
       and pcre_get_substring_list() are provided for extracting captured substrings as new, sep-
       arate,  zero-terminated	strings.  These functions identify substrings by number. The next
       section describes functions for extracting named substrings.

       A substring that contains a binary zero is correctly extracted  and  has  a  further  zero
       added  on the end, but the result is not, of course, a C string.  However, you can process
       such a string by referring to the length that is  returned  by  pcre_copy_substring()  and
       pcre_get_substring().   Unfortunately,  the  interface to pcre_get_substring_list() is not
       adequate for handling strings containing binary zeros, because the end of the final string
       is not independently indicated.

       The  first  three  arguments are the same for all three of these functions: subject is the
       subject string that has just been successfully matched, ovector is a pointer to the vector
       of  integer  offsets that was passed to pcre_exec(), and stringcount is the number of sub-
       strings that were captured by the match, including the substring that matched  the  entire
       regular	expression. This is the value returned by pcre_exec() if it is greater than zero.
       If pcre_exec() returned zero, indicating that it ran out of space in  ovector,  the  value
       passed as stringcount should be the number of elements in the vector divided by three.

       The  functions  pcre_copy_substring() and pcre_get_substring() extract a single substring,
       whose number is given as stringnumber. A value of zero extracts the substring that matched
       the   entire   pattern,	whereas  higher  values  extract  the  captured  substrings.  For
       pcre_copy_substring(), the string is placed in buffer, whose length is  given  by  buffer-
       size,  while  for  pcre_get_substring() a new block of memory is obtained via pcre_malloc,
       and its address is returned via stringptr. The yield of the function is the length of  the
       string, not including the terminating zero, or one of these error codes:

	 PCRE_ERROR_NOMEMORY	   (-6)

       The  buffer  was  too small for pcre_copy_substring(), or the attempt to get memory failed
       for pcre_get_substring().

	 PCRE_ERROR_NOSUBSTRING    (-7)

       There is no substring whose number is stringnumber.

       The pcre_get_substring_list() function extracts all available substrings and builds a list
       of  pointers  to  them.	All this is done in a single block of memory that is obtained via
       pcre_malloc. The address of the memory block is returned via listptr, which  is	also  the
       start of the list of string pointers. The end of the list is marked by a NULL pointer. The
       yield of the function is zero if all went well, or the error code

	 PCRE_ERROR_NOMEMORY	   (-6)

       if the attempt to get the memory block failed.

       When any of these functions encounter a substring that is unset,  which	can  happen  when
       capturing subpattern number n+1 matches some part of the subject, but subpattern n has not
       been used at all, they return an empty string. This can be distinguished  from  a  genuine
       zero-length  substring  by inspecting the appropriate offset in ovector, which is negative
       for unset substrings.

       The two convenience functions pcre_free_substring() and pcre_free_substring_list() can  be
       used  to  free  the  memory  returned  by  a  previous  call  of  pcre_get_substring()  or
       pcre_get_substring_list(), respectively. They do  nothing  more	than  call  the  function
       pointed	to  by pcre_free, which of course could be called directly from a C program. How-
       ever, PCRE is used in some situations where it  is  linked  via	a  special  interface  to
       another	programming  language  that  cannot use pcre_free directly; it is for these cases
       that the functions are provided.

EXTRACTING CAPTURED SUBSTRINGS BY NAME

       int pcre_get_stringnumber(const pcre *code,
	    const char *name);

       int pcre_copy_named_substring(const pcre *code,
	    const char *subject, int *ovector,
	    int stringcount, const char *stringname,
	    char *buffer, int buffersize);

       int pcre_get_named_substring(const pcre *code,
	    const char *subject, int *ovector,
	    int stringcount, const char *stringname,
	    const char **stringptr);

       To extract a substring by name, you first have to find associated  number.   For  example,
       for this pattern

	 (a+)b(?<xxx>\d+)...

       the  number  of	the  subpattern  called  "xxx"	is  2.	If the name is known to be unique
       (PCRE_DUPNAMES  was  not  set),	you  can  find	the  number  from  the	name  by  calling
       pcre_get_stringnumber(). The first argument is the compiled pattern, and the second is the
       name. The yield of the function is the subpattern number, or  PCRE_ERROR_NOSUBSTRING  (-7)
       if there is no subpattern of that name.

       Given  the  number,  you  can  extract the substring directly, or use one of the functions
       described in the previous section. For convenience, there are also two functions  that  do
       the whole job.

       Most  of  the  arguments of pcre_copy_named_substring() and pcre_get_named_substring() are
       the same as those for the similarly named functions that extract by number. As  these  are
       described in the previous section, they are not re-described here. There are just two dif-
       ferences:

       First, instead of a substring number, a substring name is given. Second, there is an extra
       argument,  given  at the start, which is a pointer to the compiled pattern. This is needed
       in order to gain access to the name-to-number translation table.

       These  functions  call  pcre_get_stringnumber(),  and  if  it  succeeds,  they  then  call
       pcre_copy_substring()  or  pcre_get_substring(), as appropriate. NOTE: If PCRE_DUPNAMES is
       set and there are duplicate names, the behaviour may not be what you want  (see	the  next
       section).

       Warning:  If  the  pattern  uses the "(?|" feature to set up multiple subpatterns with the
       same number, you cannot use names to distinguish them, because names are not  included  in
       the compiled code. The matching process uses only numbers.

DUPLICATE SUBPATTERN NAMES

       int pcre_get_stringtable_entries(const pcre *code,
	    const char *name, char **first, char **last);

       When  a	pattern  is compiled with the PCRE_DUPNAMES option, names for subpatterns are not
       required to be unique. Normally, patterns with duplicate names are such that  in  any  one
       match, only one of the named subpatterns participates. An example is shown in the pcrepat-
       tern documentation.

       When duplicates are present,  pcre_copy_named_substring()  and  pcre_get_named_substring()
       return  the  first substring corresponding to the given name that is set. If none are set,
       PCRE_ERROR_NOSUBSTRING (-7) is returned; no data is returned. The  pcre_get_stringnumber()
       function  returns  one  of  the	numbers  that are associated with the name, but it is not
       defined which it is.

       If you want to get full details of all captured substrings for a given name, you must  use
       the  pcre_get_stringtable_entries()  function. The first argument is the compiled pattern,
       and the second is the name. The third and fourth  are  pointers	to  variables  which  are
       updated by the function. After it has run, they point to the first and last entries in the
       name-to-number table for the given name. The function itself returns the  length  of  each
       entry,  or  PCRE_ERROR_NOSUBSTRING  (-7)  if  there  are  none. The format of the table is
       described above in the section entitled Information about a pattern.  Given all the  rele-
       vant  entries  for the name, you can extract each of their numbers, and hence the captured
       data, if any.

FINDING ALL POSSIBLE MATCHES

       The traditional matching function uses a similar algorithm to Perl, which  stops  when  it
       finds  the  first match, starting at a given point in the subject. If you want to find all
       possible matches, or the longest possible match, consider using the  alternative  matching
       function  (see  below) instead. If you cannot use the alternative function, but still need
       to find all possible matches, you can kludge it up by making use of the callout	facility,
       which is described in the pcrecallout documentation.

       What  you  have	to  do is to insert a callout right at the end of the pattern.	When your
       callout function is called, extract and save the current matched substring. Then return 1,
       which forces pcre_exec() to backtrack and try other alternatives. Ultimately, when it runs
       out of matches, pcre_exec() will yield PCRE_ERROR_NOMATCH.

MATCHING A PATTERN: THE ALTERNATIVE FUNCTION

       int pcre_dfa_exec(const pcre *code, const pcre_extra *extra,
	    const char *subject, int length, int startoffset,
	    int options, int *ovector, int ovecsize,
	    int *workspace, int wscount);

       The function pcre_dfa_exec() is called to match a subject string against a  compiled  pat-
       tern,  using  a	matching  algorithm that scans the subject string just once, and does not
       backtrack. This has different characteristics to the normal algorithm, and is not compati-
       ble  with  Perl.  Some  of  the features of PCRE patterns are not supported. Nevertheless,
       there are times when this kind of matching can be useful. For  a  discussion  of  the  two
       matching algorithms, see the pcrematching documentation.

       The  arguments  for the pcre_dfa_exec() function are the same as for pcre_exec(), plus two
       extras. The ovector argument is used in a different way, and this is described below.  The
       other  common  arguments are used in the same way as for pcre_exec(), so their description
       is not repeated here.

       The two additional arguments provide workspace for  the	function.  The	workspace  vector
       should  contain	at  least  20  elements.  It  is used for keeping track of multiple paths
       through the pattern tree. More workspace will be needed for patterns  and  subjects  where
       there are a lot of potential matches.

       Here is an example of a simple call to pcre_dfa_exec():

	 int rc;
	 int ovector[10];
	 int wspace[20];
	 rc = pcre_dfa_exec(
	   re,		   /* result of pcre_compile() */
	   NULL,	   /* we didn't study the pattern */
	   "some string",  /* the subject string */
	   11,		   /* the length of the subject string */
	   0,		   /* start at offset 0 in the subject */
	   0,		   /* default options */
	   ovector,	   /* vector of integers for substring information */
	   10,		   /* number of elements (NOT size in bytes) */
	   wspace,	   /* working space vector */
	   20); 	   /* number of elements (NOT size in bytes) */

   Option bits for pcre_dfa_exec()

       The  unused  bits  of the options argument for pcre_dfa_exec() must be zero. The only bits
       that  may  be  set  are	 PCRE_ANCHORED,   PCRE_NEWLINE_xxx,   PCRE_NOTBOL,   PCRE_NOTEOL,
       PCRE_NOTEMPTY,  PCRE_NO_UTF8_CHECK, PCRE_PARTIAL, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART.
       All but the last three of these are the same as for pcre_exec(), so their  description  is
       not repeated here.

	 PCRE_PARTIAL

       This  has the same general effect as it does for pcre_exec(), but the details are slightly
       different.   When   PCRE_PARTIAL   is   set   for   pcre_dfa_exec(),   the   return   code
       PCRE_ERROR_NOMATCH  is  converted  into	PCRE_ERROR_PARTIAL  if	the end of the subject is
       reached, there have been no complete matches, but there is still  at  least  one  matching
       possibility. The portion of the string that provided the partial match is set as the first
       matching string.

	 PCRE_DFA_SHORTEST

       Setting the PCRE_DFA_SHORTEST option causes the matching algorithm to stop as soon  as  it
       has found one match. Because of the way the alternative algorithm works, this is necessar-
       ily the shortest possible match at the  first  possible	matching  point  in  the  subject
       string.

	 PCRE_DFA_RESTART

       When  pcre_dfa_exec() is called with the PCRE_PARTIAL option, and returns a partial match,
       it is possible to call it again, with additional subject characters, and have it  continue
       with the same match. The PCRE_DFA_RESTART option requests this action; when it is set, the
       workspace and wscount options must reference the same vector as before because data  about
       the  match  so far is left in them after a partial match. There is more discussion of this
       facility in the pcrepartial documentation.

   Successful returns from pcre_dfa_exec()

       When pcre_dfa_exec() succeeds, it may have matched more than one substring in the subject.
       Note,  however,	that all the matches from one run of the function start at the same point
       in the subject. The shorter matches are all initial substrings of the longer matches.  For
       example, if the pattern

	 <.*>

       is matched against the string

	 This is <something> <something else> <something further> no more

       the three matched strings are

	 <something>
	 <something> <something else>
	 <something> <something else> <something further>

       On  success,  the yield of the function is a number greater than zero, which is the number
       of matched substrings. The substrings themselves are returned in ovector. Each string uses
       two  elements;  the  first is the offset to the start, and the second is the offset to the
       end. In fact, all the strings have the same start offset. (Space could have been saved  by
       giving  this  only  once,  but  it  was	decided to retain some compatibility with the way
       pcre_exec() returns data, even though the meaning of the strings is different.)

       The strings are returned in reverse order of length; that is, the longest matching  string
       is given first. If there were too many matches to fit into ovector, the yield of the func-
       tion is zero, and the vector is filled with the longest matches.

   Error returns from pcre_dfa_exec()

       The pcre_dfa_exec() function returns a negative number when it fails.  Many of the  errors
       are the same as for pcre_exec(), and these are described above.	There are in addition the
       following errors that are specific to pcre_dfa_exec():

	 PCRE_ERROR_DFA_UITEM	   (-16)

       This return is given if pcre_dfa_exec() encounters an item in the pattern that it does not
       support, for instance, the use of \C or a back reference.

	 PCRE_ERROR_DFA_UCOND	   (-17)

       This  return is given if pcre_dfa_exec() encounters a condition item that uses a back ref-
       erence for the condition, or a test for recursion in a specific group. These are not  sup-
       ported.

	 PCRE_ERROR_DFA_UMLIMIT    (-18)

       This return is given if pcre_dfa_exec() is called with an extra block that contains a set-
       ting of the match_limit field. This is not supported (it is meaningless).

	 PCRE_ERROR_DFA_WSSIZE	   (-19)

       This return is given if pcre_dfa_exec() runs out of space in the workspace vector.

	 PCRE_ERROR_DFA_RECURSE    (-20)

       When a recursive subpattern is processed, the matching function calls itself  recursively,
       using  private vectors for ovector and workspace. This error is given if the output vector
       is not large enough. This should be extremely rare, as a vector of size 1000 is used.

SEE ALSO

       pcrebuild(3),	pcrecallout(3),    pcrecpp(3)(3),    pcrematching(3),	  pcrepartial(3),
       pcreposix(3), pcreprecompile(3), pcresample(3), pcrestack(3).

AUTHOR

       Philip Hazel
       University Computing Service
       Cambridge CB2 3QH, England.

REVISION

       Last updated: 11 April 2009
       Copyright (c) 1997-2009 University of Cambridge.

										       PCREAPI(3)
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