Few More String functions..

String Length
int strlen( char *s )
{
    char *ptr = s;

    while( *ptr++ );
    return( ptr-s );
}

String Copy
char *strcpy( char *s, char *t )
{
    char *ptr=s;
    while( *s++ = *t++ );
    return( ptr );
}

String Cat
char *strcat( char *s, char *t )
{
    char *ptr=s;

    while( *s++ );
    while( *s++ = *t++ );
    return( ptr );
}

String Compare
int strcmp( char *s, char *t )
{
    int n;
    while ((n = *s - *t++) == 0 && *s++);
    return( n );
}