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SCANF(3)	       FreeBSD Library Functions Manual		      SCANF(3)

NAME
     scanf, fscanf, sscanf, vscanf, vsscanf, vfscanf --	input format conver-
     sion

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() functions respec-
     tively.  Each successive pointer argument must correspond properly	with
     each successive conversion	specifier (but see the * conversion 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 conversion 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.

     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).

     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).

     l (ell)  Indicates	that the conversion will be one	of dioux or n and the
	      next pointer is a	pointer	to a long int (rather than int), that
	      the conversion will be one of a, e, f, or	g and the next pointer
	      is a pointer to double (rather than float), or that the conver-
	      sion will	be one of c, s or [ and	the next pointer is a pointer
	      to an array of wchar_t (rather than char).

     ll	(ell ell)
	      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).

     L	      Indicates	that the conversion will be one	of a, e, f, or g and
	      the next pointer is a pointer to long double.

     j	      Indicates	that the conversion will be one	of dioux or n and the
	      next pointer is a	pointer	to a intmax_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).

     q	      (deprecated.)  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).

     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 bytes are scanned in processing the
     conversion.  In the case of the lc, ls and	l[ conversions,	the field
     width specifies the maximum number	of multibyte characters	that will be
     scanned.  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.

     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 oth-
	   erwise.  Only characters that correspond to the base	are used.

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

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

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

     a,	A, e, E, f, F, g, G
	   Matches a floating-point number in the style	of strtod(3).  The
	   next	pointer	must be	a pointer to float (unless l or	L is speci-
	   fied.)

     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 terminating NUL character.  The
	   input string	stops at white space or	at the maximum field width,
	   whichever occurs first.

	   If an l qualifier is	present, the next pointer must be a pointer to
	   wchar_t, into which the input will be placed	after conversion by
	   mbrtowc(3).

     S	   The same as ls.

     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.

	   If an l qualifier is	present, the next pointer must be a pointer to
	   wchar_t, into which the input will be placed	after conversion by
	   mbrtowc(3).

     C	   The same as lc.

     [	   Matches a nonempty sequence of characters from the specified	set of
	   accepted characters;	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 ] charac-
	   ter.	 The set excludes those	characters 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 special; 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 cir-
	   cumflex, in)	set or when the	field width runs out.

	   If an l qualifier is	present, the next pointer must be a pointer to
	   wchar_t, into which the input will be placed	after conversion by
	   mbrtowc(3).

     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.

     The decimal point character is defined in the program's locale (category
     LC_NUMERIC).

     For backwards compatibility, a ``conversion'' of `%\0' causes an immedi-
     ate return	of EOF.

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 fail-
     ure.  Zero	indicates that,	while there was	input available, no conver-
     sions 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 successfully completed	is
     returned.

SEE ALSO
     getc(3), mbrtowc(3), printf(3), strtod(3),	strtol(3), strtoul(3),
     wscanf(3)

STANDARDS
     The functions fscanf(), scanf(), sscanf(),	vfscanf(), vscanf() and
     vsscanf() conform to ISO/IEC 9899:1999 (``ISO C99'').

BUGS
     Earlier implementations of	scanf treated %D, %E, %F, %O and %X as their
     lowercase equivalents with	an l modifier.	In addition, scanf treated an
     unknown conversion	character as %d	or %D, depending on its	case.  This
     functionality has been removed.

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

     The %n$ modifiers for positional arguments	are not	implemented.

     The scanf family of functions do not correctly handle multibyte charac-
     ters in the format	argument.

FreeBSD	9.3			January	4, 2003			   FreeBSD 9.3

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | CONVERSIONS | RETURN VALUES | SEE ALSO | STANDARDS | BUGS

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