mblen()

Count the bytes in a multibyte character

Synopsis:

#include <stdlib.h>

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

Arguments:

s: NULL (see below), or a pointer to a multibyte character.
n: The maximum number of bytes that you want to count.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The mblen() function counts the number of bytes in the multibyte character pointed to by s, to a maximum of n bytes.

The mbrlen() function is a restartable version of mblen().

Returns:

If s is NULL, mblen() determines whether or not the character encoding is state-dependent:

0

The mblen() function uses locale-specific multibyte character encoding that's not state-dependent.

≠ 0

Character is state-dependent.
If s isn't NULL:

0

s points to the null character.

-1

The next n bytes don't form a valid multibyte character.

> 0

The number of bytes that comprise the multibyte character (if the next n or fewer bytes form a valid multibyte character).

Examples:

#include <stdio.h>
#include <stdlib.h>

int main( void )
{
    int len;
    char *mbs = "string";

    printf( "Character encodings do " );
    if( !mblen( NULL, 0 ) ) {
        printf( "not " );
    }
    printf( "have state-dependent \nencoding.\n" );

    len = mblen( "string", 6 );
    if( len != -1 ) {
        mbs[len] = '\0';
        printf( "Multibyte char '%s'(%d)\n", mbs, len );
    }
    
    return EXIT_SUCCESS;
}

This produces the output:

Character encodings do not have state-dependent 
encoding.
Multibyte char 's'(1)

Classification:

ANSI, POSIX 1003.1

Safety:
Cancellation point	No
Interrupt handler	No
Signal handler	Yes
Thread	Yes