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SCANF(3)               FreeBSD 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() functions
     respectively.  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 conversion 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
           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.

     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
           specified.)

     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 ]
           character.  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 circumflex, 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
     immediate 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
     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 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
     characters in the format argument.

FreeBSD 11.0-PRERELEASE         January 4, 2003        FreeBSD 11.0-PRERELEASE

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

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