MBLEN(3)                                                                Linux Programmer's Manual                                                               MBLEN(3)

NAME
       mblen - determine number of bytes in next multibyte character

SYNOPSIS
       #include <stdlib.h>

       int mblen(const char *s, size_t n);

DESCRIPTION
       If  s  is  not  NULL, the mblen() function inspects at most n bytes of the multibyte string starting at s and extracts the next complete multibyte character.  It
       uses a static anonymous shift state known only to the mblen() function.  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 returns 0.

       If  the  n  bytes  starting  at  s  do  not  contain  a  complete multibyte character, mblen() returns -1.  This can happen even if n is greater than or equal to
       MB_CUR_MAX, if the multibyte string contains redundant shift sequences.

       If the multibyte string starting at s contains an invalid multibyte sequence before the next complete character, mblen() also returns -1.

       If s is NULL, the mblen() function resets the shift state, known to only 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
       The mblen() function returns the number of bytes parsed from the multibyte sequence starting at s, if a non-null wide character was recognized.  It returns 0, if
       a null wide character was recognized.  It returns -1, if an invalid multibyte sequence was encountered or if it couldn't parse a complete multibyte character.

ATTRIBUTES
       For an explanation of the terms used in this section, see attributes(7).

       ┌───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┬───────────────┬────────────────┐
       │Interface                                                                                                                      │ Attribute     │ Value          │
       ├───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┼───────────────┼────────────────┤
       │mblen()                                                                                                                        │ Thread safety │ MT-Unsafe race │
       └───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┴───────────────┴────────────────┘

CONFORMING TO
       POSIX.1-2001, POSIX.1-2008, C99.

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

       The function mbrlen(3) provides a better interface to the same functionality.

SEE ALSO
       mbrlen(3)

GNU                                                                            2021-03-22                                                                       MBLEN(3)