SWSCANF(3)

NAME
4.63 `swscanf', `fwscanf', `wscanf'--scan and format wide character input

SYNOPSIS
     #include <stdio.h>
     int wscanf(const wchar_t *FORMAT, ...);
     int fwscanf(FILE *FD, const wchar_t *FORMAT, ...);
     int swscanf(const wchar_t *STR, const wchar_t *FORMAT, ...);
     int _wscanf_r(struct _reent *PTR, const wchar_t *FORMAT, ...);
     int _fwscanf_r(struct _reent *PTR, FILE *FD,
         const wchar_t *FORMAT, ...);
     int _swscanf_r(struct _reent *PTR, const wchar_t *STR,
         const wchar_t *FORMAT, ...);

DESCRIPTION
`wscanf' scans a series of input fields from standard input, one wide character at a time. Each field is interpreted according to a format specifier passed to `wscanf' in the format string at `*FORMAT'. `wscanf' stores the interpreted input from each field at the address passed to it as the corresponding argument following FORMAT. You must supply the same number of format specifiers and address arguments as there are input fields.
   There must be sufficient address arguments for the given format specifiers; if not the results are unpredictable and likely disasterous. Excess address arguments are merely ignored.
   `wscanf' often produces unexpected results if the input diverges from an expected pattern. Since the combination of `gets' or `fgets' followed by `swscanf' is safe and easy, that is the preferred way to be certain that a program is synchronized with input at the end of a line.
   `fwscanf' and `swscanf' are identical to `wscanf', other than the source of input: `fwscanf' reads from a file, and `swscanf' from a string.
   The routines `_wscanf_r', `_fwscanf_r', and `_swscanf_r' are reentrant versions of `wscanf', `fwscanf', and `swscanf' that take an additional first argument pointing to a reentrancy structure.
   The string at `*FORMAT' is a wide character sequence composed of zero or more directives. Directives are composed of one or more whitespace characters, non-whitespace characters, and format specifications.
   Whitespace characters are blank (` '), tab (` '), or newline (`). When `wscanf' encounters a whitespace character in the format string it will read (but not store) all consecutive whitespace characters up to the next non-whitespace character in the input.
   Non-whitespace characters are all other ASCII characters except the percent sign (`%'). When `wscanf' encounters a non-whitespace character in the format string it will read, but not store a matching non-whitespace character.
   Format specifications tell `wscanf' to read and convert characters from the input field into specific types of values, and store then in the locations specified by the address arguments.
   Trailing whitespace is left unread unless explicitly matched in the format string.
   The format specifiers must begin with a percent sign (`%') and have the following form:
            %[*][WIDTH][SIZE]TYPE
   Each format specification begins with the percent character (`%'). The other fields are: `*'
     an optional marker; if present, it suppresses interpretation and
     assignment of this input field. `WIDTH'
     an optional maximum field width: a decimal integer, which controls
     the maximum number of characters that will be read before
     converting the current input field. If the input field has fewer
     than WIDTH characters, `wscanf' reads all the characters in the
     field, and then proceeds with the next field and its format
     specification.
     If a whitespace or a non-convertable wide character occurs before
     WIDTH character are read, the characters up to that character are
     read, converted, and stored. Then `wscanf' proceeds to the next
     format specification. `size'
     `h', `j', `l', `L', `t', and `z' are optional size characters
     which override the default way that `wscanf' interprets the data
     type of the corresponding argument.
          Modifier Type(s)
             hh d, i, o, u, x, n convert input to char,
                        store in char object
             h d, i, o, u, x, n convert input to short,
                        store in short object
             h e, f, c, s, p no effect
             j d, i, o, u, x, n convert input to intmax_t,
                        store in intmax_t object
             j all others no effect
             l d, i, o, u, x, n convert input to long,
                        store in long object
             l e, f, g convert input to double
                        store in a double object
             l c, s, [ the input is stored in a wchar_t object
             l p no effect
             ll d, i, o, u, x, n convert to long long,
                        store in long long
             L d, i, o, u, x, n convert to long long,
                        store in long long
             L e, f, g, E, G convert to long double,
                        store in long double
             L all others no effect
             t d, i, o, u, x, n convert input to ptrdiff_t,
                        store in ptrdiff_t object
             t all others no effect
             z d, i, o, u, x, n convert input to size_t,
                        store in size_t object
             z all others no effect `TYPE'
     A character to specify what kind of conversion `wscanf' performs.
     Here is a table of the conversion characters:
    `%'
          No conversion is done; the percent character (`%') is stored.
    `c'
          Scans one wide character. Corresponding ARG: `(char *arg)'.
          Otherwise, if an `l' specifier is present, the corresponding
          ARG is a `(wchar_t *arg)'.
    `s'
          Reads a character string into the array supplied.
          Corresponding ARG: `(char arg[])'. If an `l' specifier is
          present, the corresponding ARG is a `(wchar_t *arg)'.
    `[PATTERN]'
          Reads a non-empty character string into memory starting at
          ARG. This area must be large enough to accept the sequence
          and a terminating null character which will be added
          automatically. (PATTERN is discussed in the paragraph
          following this table). Corresponding ARG: `(char *arg)'. If
          an `l' specifier is present, the corresponding ARG is a
          `(wchar_t *arg)'.
    `d'
          Reads a decimal integer into the corresponding ARG: `(int
          *arg)'.
    `o'
          Reads an octal integer into the corresponding ARG: `(int
          *arg)'.
    `u'
          Reads an unsigned decimal integer into the corresponding ARG:
          `(unsigned int *arg)'.
    `x,X'
          Read a hexadecimal integer into the corresponding ARG: `(int
          *arg)'.
    `e, f, g'
          Read a floating-point number into the corresponding ARG:
          `(float *arg)'.
    `E, F, G'
          Read a floating-point number into the corresponding ARG:
          `(double *arg)'.
    `i'
          Reads a decimal, octal or hexadecimal integer into the
          corresponding ARG: `(int *arg)'.
    `n'
          Stores the number of characters read in the corresponding
          ARG: `(int *arg)'.
    `p'
          Stores a scanned pointer. ANSI C leaves the details to each
          implementation; this implementation treats `%p' exactly the
          same as `%U'. Corresponding ARG: `(void **arg)'.
     A PATTERN of characters surrounded by square brackets can be used
     instead of the `s' type character. PATTERN is a set of characters
     which define a search set of possible characters making up the
     `wscanf' input field. If the first character in the brackets is a
     caret (`^'), the search set is inverted to include all ASCII
     characters except those between the brackets. There is no range
     facility as is defined in the corresponding non-wide character
     scanf functions. Ranges are not part of the POSIX standard.
     Here are some PATTERN examples:
    `%[abcd]'
          matches wide character strings containing only `a', `b', `c',
          and `d'.
    `%[^abcd]'
          matches wide character strings containing any characters
          except `a', `b', `c', or `d'.
    `%[A-DW-Z]'
          Note: No wide character ranges, so this expression matches
          wide character strings containing `A', `-', `D', `W', `Z'.
     Floating point numbers (for field types `e', `f', `g', `E', `F',
     `G') must correspond to the following general form:
                  [+/-] ddddd[.]ddd [E|e[+|-]ddd]
     where objects inclosed in square brackets are optional, and `ddd'
     represents decimal, octal, or hexadecimal digits.

RETURNS
`wscanf' returns the number of input fields successfully scanned, converted and stored; the return value does not include scanned fields which were not stored.
   If `wscanf' attempts to read at end-of-file, the return value is `EOF'.
   If no fields were stored, the return value is `0'.
   `wscanf' might stop scanning a particular field before reaching the normal field end character, or may terminate entirely.
   `wscanf' stops scanning and storing the current field and moves to the next input field (if any) in any of the following situations:
   * The assignment suppressing character (`*') appears after the `%'
     in the format specification; the current input field is scanned
     but not stored.
   * WIDTH characters have been read (WIDTH is a width specification, a
     positive decimal integer).
   * The next wide character read cannot be converted under the the
     current format (for example, if a `Z' is read when the format is
     decimal).
   * The next wide character in the input field does not appear in the
     search set (or does appear in the inverted search set).
   When `wscanf' stops scanning the current input field for one of these reasons, the next character is considered unread and used as the first character of the following input field, or the first character in a subsequent read operation on the input.
   `wscanf' will terminate under the following circumstances:
   * The next wide character in the input field conflicts with a
     corresponding non-whitespace character in the format string.
   * The next wide character in the input field is `WEOF'.
   * The format string has been exhausted.
   When the format string contains a wide character sequence that is not part of a format specification, the same wide character sequence must appear in the input; `wscanf' will scan but not store the matched characters. If a conflict occurs, the first conflicting wide character remains in the input as if it had never been read.

PORTABILITY
`wscanf' is C99, POSIX-1.2008.
   Supporting OS subroutines required: `close', `fstat', `isatty', `lseek', `read', `sbrk', `write'.

SEE ALSO
swscanf is part of the library. The full documentation for is maintained as a Texinfo manual. If info and are properly installed at your site, the command

    info

will give you access to the complete manual.