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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ATTRIBUTES | VERSIONS | STANDARDS | HISTORY | NOTES | SEE ALSO | COLOPHON |
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mbtowc(3) Library Functions Manual mbtowc(3)
mbtowc - convert a multibyte sequence to a wide character
Standard C library (libc, -lc)
#include <stdlib.h>
int mbtowc(size_t n;
wchar_t *restrict pwc, const char s[restrict n], size_t n);
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.
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.
For an explanation of the terms used in this section, see
attributes(7).
┌───────────────────────────────┬───────────────┬────────────────┐
│ Interface │ Attribute │ Value │
├───────────────────────────────┼───────────────┼────────────────┤
│ mbtowc() │ Thread safety │ MT-Unsafe race │
└───────────────────────────────┴───────────────┴────────────────┘
This function is not multithread safe. The function mbrtowc(3)
provides a better interface to the same functionality.
C11, POSIX.1-2008.
POSIX.1-2001, C99.
The behavior of mbtowc() depends on the LC_CTYPE category of the
current locale.
MB_CUR_MAX(3), mblen(3), mbrtowc(3), mbstowcs(3), wcstombs(3),
wctomb(3)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
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Linux man-pages 6.15 2025-06-28 mbtowc(3)
Pages that refer to this page: btowc(3), MB_CUR_MAX(3), mbstowcs(3), wcstombs(3), wctomb(3)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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