c语言生成随机uuid编码

/**
 * Create random UUID
 *
 * @param buf - buffer to be filled with the uuid string
 */
char *random_uuid( char buf[37] )
{
    const char *c = \"89ab\";
    char *p = buf;
    int n;

    for( n = 0; n < 16; ++n )
    {
        int b = rand()%255;

        switch( n )
        {
            case 6:
                sprintf(
                    p,
                    \"4%x\",
                    b%15 );
                break;
            case 8:
                sprintf(
                    p,
                    \"%c%x\",
                    c[rand()%strlen( c )],
                    b%15 );
                break;
            default:
                sprintf(
                    p,
                    \"%02x\",
                    b );
                break;
        }

        p += 2;

        switch( n )
        {
            case 3:
            case 5:
            case 7:
            case 9:
                *p++ = \'-\';
                break;
        }
    }

    *p = 0;

    return buf;
}