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NetBSD 6.1.5 - man page for vscanf (netbsd section 3)

SCANF(3)			   BSD Library Functions Manual 			 SCANF(3)

NAME
     scanf, fscanf, sscanf, vscanf, vsscanf, vfscanf -- input format conversion

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <stdio.h>

     int
     scanf(const char * restrict format, ...);

     int
     fscanf(FILE * restrict stream, const char * restrict format, ...);

     int
     sscanf(const char * restrict str, const char * restrict format, ...);

     #include <stdarg.h>

     int
     vscanf(const char * restrict format, va_list ap);

     int
     vsscanf(const char * restrict str, const char * restrict format, va_list ap);

     int
     vfscanf(FILE * restrict stream, const char * restrict format, va_list ap);

DESCRIPTION
     The scanf() family of functions scans input according to a format as described below.  This
     format may contain conversion specifiers; the results from such conversions, if any, are
     stored through the pointer arguments.

     The scanf() function reads input from the standard input stream stdin, fscanf() reads input
     from the stream pointer stream, and sscanf() reads its input from the character string
     pointed to by str.  The vfscanf() function is analogous to vfprintf(3) and reads input from
     the stream pointer stream using a variable argument list of pointers (see stdarg(3)).  The
     vscanf() function scans a variable argument list from the standard input and the vsscanf()
     function scans it from a string; these are analogous to the vprintf() and vsprintf() func-
     tions respectively.

     Each successive pointer argument must correspond properly with each successive conversion
     specifier (but see `suppression' below).  All conversions are introduced by the % (percent
     sign) character.  The format string may also contain other characters.  White space (such as
     blanks, tabs, or newlines) in the format string match any amount of white space, including
     none, in the input.  Everything else matches only itself.	Scanning stops when an input
     character does not match such a format character.	Scanning also stops when an input conver-
     sion cannot be made (see below).

CONVERSIONS
     Following the % character introducing a conversion there may be a number of flag characters,
     as follows:

     *	     Suppresses assignment.  The conversion that follows occurs as usual, but no pointer
	     is used; the result of the conversion is simply discarded.

     h	     Indicates that the conversion will be one of dioux or n and the next pointer is a
	     pointer to a short int (rather than int).

     hh      Indicates that the conversion will be one of dioux or n and the next pointer is a
	     pointer to a char (rather than int).

     j	     Indicates that the conversion will be one of dioux or n and the next pointer is a
	     pointer to an intmax_t (rather than int).

     l	     Indicates either that the conversion will be one of dioux or n and the next pointer
	     is a pointer to a long int (rather than int), or that the conversion will be one of
	     efg and the next pointer is a pointer to double (rather than float).

     ll      Indicates that the conversion will be one of dioux or n and the next pointer is a
	     pointer to a long long int (rather than int).

     q	     Indicates that the conversion will be one of dioux or n and the next pointer is a
	     pointer to a quad_t (rather than int).

     t	     Indicates that the conversion will be one of dioux or n and the next pointer is a
	     pointer to a ptrdiff_t (rather than int).

     z	     Indicates that the conversion will be one of dioux or n and the next pointer is a
	     pointer to a size_t (rather than int).

     L	     Indicates that the conversion will be efg and the next pointer is a pointer to long
	     double.

     In addition to these flags, there may be an optional maximum field width, expressed as a
     decimal integer, between the % and the conversion.  If no width is given, a default of
     `infinity' is used (with one exception, below); otherwise at most this many characters are
     scanned in processing the conversion.  Before conversion begins, most conversions skip white
     space; this white space is not counted against the field width.

     The following conversions are available:

     %	   Matches a literal `%'.  That is, `%%' in the format string matches a single input `%'
	   character.  No conversion is done, and assignment does not occur.

     d	   Matches an optionally signed decimal integer; the next pointer must be a pointer to
	   int.

     D	   Equivalent to ld; this exists only for backwards compatibility.

     i	   Matches an optionally signed integer; the next pointer must be a pointer to int.  The
	   integer is read in base 16 if it begins with '0x' or '0X', in base 8 if it begins with
	   '0', and in base 10 otherwise.  Only characters that correspond to the base are used.

     o	   Matches an octal integer; the next pointer must be a pointer to unsigned int.

     O	   Equivalent to lo; this exists for backwards compatibility.

     u	   Matches an optionally signed decimal integer; the next pointer must be a pointer to
	   unsigned int.

     x	   Matches an optionally signed hexadecimal integer; the next pointer must be a pointer
	   to unsigned int.

     X	   Equivalent to x.

     f	   Matches an optionally signed floating-point number; the next pointer must be a pointer
	   to float.

     e	   Equivalent to f.

     g	   Equivalent to f.

     E	   Equivalent to f.

     G	   Equivalent to f.

     s	   Matches a sequence of non-white-space characters; the next pointer must be a pointer
	   to char, and the array must be large enough to accept all the sequence and the termi-
	   nating NUL character.  The input string stops at white space or at the maximum field
	   width, whichever occurs first.

     c	   Matches a sequence of width count characters (default 1); the next pointer must be a
	   pointer to char, and there must be enough room for all the characters (no terminating
	   NUL is added).  The usual skip of leading white space is suppressed.  To skip white
	   space first, use an explicit space in the format.

     [	   Matches a nonempty sequence of characters from the specified set of accepted charac-
	   ters; the next pointer must be a pointer to char, and there must be enough room for
	   all the characters in the string, plus a terminating NUL character.	The usual skip of
	   leading white space is suppressed.  The string is to be made up of characters in (or
	   not in) a particular set; the set is defined by the characters between the open
	   bracket [ character and a close bracket ] character.  The set excludes those charac-
	   ters if the first character after the open bracket is a circumflex ^.  To include a
	   close bracket in the set, make it the first character after the open bracket or the
	   circumflex; any other position will end the set.  The hyphen character - is also spe-
	   cial; when placed between two other characters, it adds all intervening characters to
	   the set.  To include a hyphen, make it the last character before the final close
	   bracket.  For instance, '[^]0-9-]' means the set `everything except close bracket,
	   zero through nine, and hyphen'.  The string ends with the appearance of a character
	   not in the (or, with a circumflex, in) set or when the field width runs out.

     p	   Matches a pointer value (as printed by '%p' in printf(3)); the next pointer must be a
	   pointer to void.

     n	   Nothing is expected; instead, the number of characters consumed thus far from the
	   input is stored through the next pointer, which must be a pointer to int.  This is not
	   a conversion, although it can be suppressed with the * flag.

     For backwards compatibility, other conversion characters (except '\0') are taken as if they
     were '%d' or, if uppercase, '%ld', and a `conversion' of '%\0' causes an immediate return of
     EOF.

     The format string specifier macros described in inttypes(3) should be used for the standard
     ``C99'' fixed-size integers documented in stdint(3).

RETURN VALUES
     These functions return the number of input items assigned, which can be fewer than provided
     for, or even zero, in the event of a matching failure.  Zero indicates that, while there was
     input available, no conversions were assigned; typically this is due to an invalid input
     character, such as an alphabetic character for a '%d' conversion.	The value EOF is returned
     if an input failure occurs before any conversion such as an end-of-file occurs.  If an error
     or end-of-file occurs after conversion has begun, the number of conversions which were suc-
     cessfully completed is returned.

SEE ALSO
     getc(3), inttypes(3), printf(3), strtod(3), strtol(3), strtoul(3)

STANDARDS
     The functions fscanf(), scanf(), and sscanf() conform to ISO/IEC 9899:1990 (``ISO C90'').
     The %j, %t and %z conversion format modifiers conform to ISO/IEC 9899:1999 (``ISO C99'').
     The vfscanf(), vscanf() and vsscanf() functions conform to ISO/IEC 9899:1999 (``ISO C99'').

HISTORY
     The functions vscanf(), vsscanf() and vfscanf() appeared in 4.4BSD or even 4.3BSD.

NOTES
     All of the backwards compatibility formats will be removed in the future.

BUGS
     Numerical strings are truncated to 512 characters; for example, %f and %d are implicitly
     %512f and %512d.

BSD					  March 21, 2010				      BSD


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