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mblen
Determines the number of bytes in a multibyte character.
Syntax
#include <stdlib.h>
int mblen(const char *s, size_t n);
Parameters
s A pointer to a single multibyte character.
n A variable of type size_t that controls the number of
characters that mblen searches when scanning for a
multibyte character. This argument is typically set to
MB_CUR_MAX.
Return Values
>0 The length of the multibyte character to which s points.
-1 The s parameter does not point to a valid multibyte
character.
=0 The s parameter is a null pointer and multibyte character
encodings are not state-dependent, or s points to a null
character.
Description
The mblen function examines the multibyte character pointed to by s. If
a valid multibyte character is recognized within n bytes from the
location pointed to by s, the length of the multibyte character is
returned.
This function retains state information. Multibyte encodings can be
state-dependent, employing "shift characters" to alter the meaning of
subsequent characters. The shift state is persistent between calls to
the routines for processing extended character sets unless the LC_CTYPE
category of the locale is changed.
Calling this function with the s argument set to NULL resets the function
to its initial state. When using a NULL pointer to clear the shift
state, zero is returned if the multibyte shift state was previously
clear. A nonzero value is returned if the locale-specific shift state
was previously set.
Locale-specific character sets that are too large to be represented
within one byte are handled in ANSI C by using extended character sets.
Extended character sets have two representations, the internal
representation, and the external representation. The external
representation is a multibyte character. The multibyte character is a
sequence of normal characters used to represent the locale-specific
extended character. The internal representation of this multibyte
character is a wide character of type wchar_t. The maximum number of
bytes in a multibyte character in the current locale (see also LC_CTYPE)
is given by the macro MB_CUR_MAX.
See Also
wchar_t, LC_CTYPE, MB_CUR_MAX, mbtowc(), wctomb(), mbstowcs(),
wcstombs(), ANSI C 4.10.7.1