STRTOK(P)						     POSIX Programmer's Manual							 STRTOK(P)

NAME

       strtok, strtok_r - split string into tokens

SYNOPSIS

       #include <string.h>

       char *strtok(char *restrict s1, const char *restrict s2);

       char *strtok_r(char *restrict s, const char *restrict sep,
	      char **restrict lasts);

DESCRIPTION

       For  strtok():	 The  functionality described on this reference page is aligned with the ISO C standard. Any conflict between the require-
       ments described here and the ISO C standard is unintentional. This volume of IEEE Std 1003.1-2001 defers to the ISO C standard.

       A sequence of calls to strtok() breaks the string pointed to by s1 into a sequence of tokens, each of which is delimited by a byte from the
       string pointed to by s2. The first call in the sequence has s1 as its first argument, and is followed by calls with a null pointer as their
       first argument.	The separator string pointed to by s2 may be different from call to call.

       The first call in the sequence searches the string pointed to by s1 for the first byte that is  not  contained  in  the	current  separator
       string pointed to by s2. If no such byte is found, then there are no tokens in the string pointed to by s1 and strtok() shall return a null
       pointer. If such a byte is found, it is the start of the first token.

       The strtok() function then searches from there for a byte that is contained in the current separator string. If no such byte is found,  the
       current token extends to the end of the string pointed to by s1, and subsequent searches for a token shall return a null pointer. If such a
       byte is found, it is overwritten by a null byte, which terminates the current token. The strtok() function saves a pointer to the following
       byte, from which the next search for a token shall start.

       Each  subsequent  call,	with  a  null  pointer	as the value of the first argument, starts searching from the saved pointer and behaves as
       described above.

       The implementation shall behave as if no function defined in this volume of IEEE Std 1003.1-2001 calls strtok().

       The strtok() function need not be reentrant. A function that is not required to be reentrant is not required to be thread-safe.

       The strtok_r() function considers the null-terminated string s as a sequence of zero or more text tokens separated by spans of one or  more
       characters  from  the separator string sep.  The argument lasts points to a user-provided pointer which points to stored information neces-
       sary for strtok_r() to continue scanning the same string.

       In the first call to strtok_r(), s points to a null-terminated string, sep to a null-terminated string of  separator  characters,  and  the
       value  pointed  to  by lasts is ignored.  The strtok_r() function shall return a pointer to the first character of the first token, write a
       null character into s immediately following the returned token, and update the pointer to which lasts points.

       In subsequent calls, s is a NULL pointer and lasts shall be unchanged from the previous call so that subsequent calls  shall  move  through
       the  string  s,	returning  successive  tokens until no tokens remain. The separator string sep may be different from call to call. When no
       token remains in s, a NULL pointer shall be returned.

RETURN VALUE

       Upon successful completion, strtok() shall return a pointer to the first byte of a token. Otherwise, if there is no token,  strtok()  shall
       return a null pointer.

       The strtok_r() function shall return a pointer to the token found, or a NULL pointer when no token is found.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

   Searching for Word Separators
       The following example searches for tokens separated by <space>s.

	      #include <string.h>
	      ...
	      char *token;
	      char *line = "LINE TO BE SEPARATED";
	      char *search = " ";

	      /* Token will point to "LINE". */
	      token = strtok(line, search);

	      /* Token will point to "TO". */
	      token = strtok(NULL, search);

   Breaking a Line
       The  following  example uses strtok() to break a line into two character strings separated by any combination of <space>s, <tab>s, or <new-
       line>s.

	      #include <string.h>
	      ...
	      struct element {
		  char *key;
		  char *data;
	      };
	      ...
	      char line[LINE_MAX];
	      char *key, *data;
	      ...
	      key = strtok(line, "    
");
	      data = strtok(NULL, "   
");
	      ...

APPLICATION USAGE

       The strtok_r() function is thread-safe and stores its state in a user-supplied buffer instead of possibly using a static data area that may
       be overwritten by an unrelated call from another thread.

RATIONALE

       The  strtok() function searches for a separator string within a larger string. It returns a pointer to the last substring between separator
       strings. This function uses static storage to keep track of the current string position between calls. The new function, strtok_r(),  takes
       an additional argument, lasts, to keep track of the current position in the string.

FUTURE DIRECTIONS

       None.

SEE ALSO

       The Base Definitions volume of IEEE Std 1003.1-2001, <string.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical  and	Electronics  Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE
       and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can  be  obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003								 STRTOK(P)