mbtowc(3) — Linux manual page

mbtowc(3)               Library Functions Manual               mbtowc(3)

NAME

       mbtowc - convert a multibyte sequence to a wide character

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #include <stdlib.h>

       int mbtowc(wchar_t *restrict pwc, const char s[restrict .n], size_t n);

DESCRIPTION

       The main case for this function is when s is not NULL and pwc is
       not NULL.  In this case, the mbtowc() function inspects at most n
       bytes of the multibyte string starting at s, extracts the next
       complete multibyte character, converts it to a wide character and
       stores it at *pwc.  It updates an internal shift state known only
       to the mbtowc() function.  If s does not point to a null byte
       ('\0'), it returns the number of bytes that were consumed from s,
       otherwise it returns 0.

       If the n bytes starting at s do not contain a complete multibyte
       character, or if they contain an invalid multibyte sequence,
       mbtowc() returns -1.  This can happen even if n >= MB_CUR_MAX, if
       the multibyte string contains redundant shift sequences.

       A different case is when s is not NULL but pwc is NULL.  In this
       case, the mbtowc() function behaves as above, except that it does
       not store the converted wide character in memory.

       A third case is when s is NULL.  In this case, pwc and n are
       ignored.  The mbtowc() function resets the shift state, only
       known to this function, to the initial state, and returns nonzero
       if the encoding has nontrivial shift state, or zero if the
       encoding is stateless.

RETURN VALUE

       If s is not NULL, the mbtowc() function returns the number of
       consumed bytes starting at s, or 0 if s points to a null byte, or
       -1 upon failure.

       If s is NULL, the mbtowc() function returns nonzero if the
       encoding has nontrivial shift state, or zero if the encoding is
       stateless.

ATTRIBUTES

       For an explanation of the terms used in this section, see
       attributes(7).
       ┌──────────────────────────────┬───────────────┬────────────────┐
       │ Interface                    │ Attribute     │ Value          │
       ├──────────────────────────────┼───────────────┼────────────────┤
       │ mbtowc()                     │ Thread safety │ MT-Unsafe race │
       └──────────────────────────────┴───────────────┴────────────────┘

VERSIONS

       This function is not multithread safe.  The function mbrtowc(3)
       provides a better interface to the same functionality.

STANDARDS

       C11, POSIX.1-2008.

HISTORY

       POSIX.1-2001, C99.

NOTES

       The behavior of mbtowc() depends on the LC_CTYPE category of the
       current locale.

SEE ALSO

       MB_CUR_MAX(3), mblen(3), mbrtowc(3), mbstowcs(3), wcstombs(3),
       wctomb(3)

COLOPHON

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Linux man-pages 6.9.1          2024-06-15                      mbtowc(3)

Pages that refer to this page: btowc(3), MB_CUR_MAX(3), mbstowcs(3), wcstombs(3), wctomb(3)

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