mbrtowc(3p) — Linux manual page


MBRTOWC(3P)               POSIX Programmer's Manual              MBRTOWC(3P)

PROLOG         top

       This manual page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior), or
       the interface may not be implemented on Linux.

NAME         top

       mbrtowc — convert a character to a wide-character code (restartable)

SYNOPSIS         top

       #include <wchar.h>

       size_t mbrtowc(wchar_t *restrict pwc, const char *restrict s,
           size_t n, mbstate_t *restrict ps);

DESCRIPTION         top

       The functionality described on this reference page is aligned with
       the ISO C standard. Any conflict between the requirements described
       here and the ISO C standard is unintentional. This volume of
       POSIX.1‐2008 defers to the ISO C standard.

       If s is a null pointer, the mbrtowc() function shall be equivalent to
       the call:

           mbrtowc(NULL, "", 1, ps)

       In this case, the values of the arguments pwc and n are ignored.

       If s is not a null pointer, the mbrtowc() function shall inspect at
       most n bytes beginning at the byte pointed to by s to determine the
       number of bytes needed to complete the next character (including any
       shift sequences). If the function determines that the next character
       is completed, it shall determine the value of the corresponding wide
       character and then, if pwc is not a null pointer, shall store that
       value in the object pointed to by pwc.  If the corresponding wide
       character is the null wide character, the resulting state described
       shall be the initial conversion state.

       If ps is a null pointer, the mbrtowc() function shall use its own
       internal mbstate_t object, which shall be initialized at program
       start-up to the initial conversion state. Otherwise, the mbstate_t
       object pointed to by ps shall be used to completely describe the
       current conversion state of the associated character sequence. The
       implementation shall behave as if no function defined in this volume
       of POSIX.1‐2008 calls mbrtowc().

       The behavior of this function is affected by the LC_CTYPE category of
       the current locale.

       The mbrtowc() function need not be thread-safe if called with a NULL
       ps argument.

       The mbrtowc() function shall not change the setting of errno if

RETURN VALUE         top

       The mbrtowc() function shall return the first of the following that

       0           If the next n or fewer bytes complete the character that
                   corresponds to the null wide character (which is the
                   value stored).

       between 1 and n inclusive
                   If the next n or fewer bytes complete a valid character
                   (which is the value stored); the value returned shall be
                   the number of bytes that complete the character.

       (size_t)−2  If the next n bytes contribute to an incomplete but
                   potentially valid character, and all n bytes have been
                   processed (no value is stored). When n has at least the
                   value of the {MB_CUR_MAX} macro, this case can only occur
                   if s points at a sequence of redundant shift sequences
                   (for implementations with state-dependent encodings).

       (size_t)−1  If an encoding error occurs, in which case the next n or
                   fewer bytes do not contribute to a complete and valid
                   character (no value is stored). In this case, [EILSEQ]
                   shall be stored in errno and the conversion state is

ERRORS         top

       The mbrtowc() function shall fail if:

       EILSEQ An invalid character sequence is detected.

       The mbrtowc() function may fail if:

       EINVAL ps points to an object that contains an invalid conversion

       The following sections are informative.

EXAMPLES         top




RATIONALE         top




SEE ALSO         top

       mbsinit(3p), mbsrtowcs(3p)

       The Base Definitions volume of POSIX.1‐2008, wchar.h(0p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) 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.unix.org/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the
       source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                 2013                         MBRTOWC(3P)

Pages that refer to this page: wchar.h(0p)fwprintf(3p)mbrlen(3p)mbsinit(3p)mbsnrtowcs(3p)mbsrtowcs(3p)