MBLEN(3) Library Functions Manual MBLEN(3)

mblen, mblen_lget number of bytes in a character

Standard C Library (libc, -lc)

#include <stdlib.h>

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

#include <stdlib.h>
#include <xlocale.h>

int
mblen_l(const char *s, size_t n, locale_t loc);

The () function computes the length, in bytes, of a multibyte character s, according to the current conversion state. Up to n bytes are examined.

A call with a null s pointer returns nonzero if the current locale requires shift states, zero otherwise. If shift states are required, the shift state is reset to the initial state.

Although the () function uses the current locale, the () function may be passed a locale directly. See xlocale(3) for more information.

If s is NULL, the mblen() function returns nonzero if shift states are supported, zero otherwise.

Otherwise, if s is not a null pointer, mblen() either returns 0 if s represents the null wide character, or returns the number of bytes processed in s, or returns -1 if no multibyte character could be recognized or converted. In this case, mblen()'s internal conversion state is undefined.

The mblen() function will fail if:

[]
An invalid multibyte sequence was detected.
[]
The internal conversion state is not valid.

mbrlen(3), mbtowc(3), multibyte(3), xlocale(3)

The mblen() function conforms to ISO/IEC 9899:1999 (“ISO C99”).

April 11, 2004 macOS 15.2