mbrlen(3) Library Functions Manual mbrlen(3)
NAME
mbrlen - determine number of bytes in next multibyte character
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#include <wchar.h>
size_t mbrlen(const char s[restrict .n], size_t n,
mbstate_t *restrict ps);
DESCRIPTION
The mbrlen() function inspects at most n bytes of the multibyte string
starting at s and extracts the next complete multibyte character. It
updates the shift state *ps. If the multibyte character is not the
null wide character, it returns the number of bytes that were consumed
from s. If the multibyte character is the null wide character, it re-
sets the shift state *ps to the initial state and returns 0.
If the n bytes starting at s do not contain a complete multibyte char-
acter, mbrlen() returns (size_t) -2. This can happen even if n >=
MB_CUR_MAX, if the multibyte string contains redundant shift sequences.
If the multibyte string starting at s contains an invalid multibyte se-
quence before the next complete character, mbrlen() returns (size_t) -1
and sets errno to EILSEQ. In this case, the effects on *ps are unde-
fined.
If ps is NULL, a static anonymous state known only to the mbrlen()
function is used instead.
RETURN VALUE
The mbrlen() function returns the number of bytes parsed from the
multibyte sequence starting at s, if a non-null wide character was rec-
ognized. It returns 0, if a null wide character was recognized. It
returns (size_t) -1 and sets errno to EILSEQ, if an invalid multibyte
sequence was encountered. It returns (size_t) -2 if it couldn't parse
a complete multibyte character, meaning that n should be increased.
ATTRIBUTES
For an explanation of the terms used in this section, see attrib-
utes(7).
┌─────────────────────────┬───────────────┬───────────────────────────┐
│ Interface │ Attribute │ Value │
├─────────────────────────┼───────────────┼───────────────────────────┤
│ mbrlen() │ Thread safety │ MT-Unsafe race:mbrlen/!ps │
└─────────────────────────┴───────────────┴───────────────────────────┘
STANDARDS
C11, POSIX.1-2008.
HISTORY
POSIX.1-2001, C99.
NOTES
The behavior of mbrlen() depends on the LC_CTYPE category of the cur-
rent locale.
SEE ALSO
mbrtowc(3)
Linux man-pages 6.7 2023-10-31 mbrlen(3)
Generated by dwww version 1.16 on Tue Dec 16 11:12:32 CET 2025.