#include <stdio.h>
#include <conio.h>
#include <string.h>

int xstrlen ( char * ) ;
void xstrcpy ( char *, char * ) ;
void xstrcat ( char *, char * ) ;
int xstrcmp ( char *, char * ) ;
void show ( char * ) ;

void main( )
{
    char s1[ ] = "kicit" ;
    char s2[ ] = "Nagpur" ;
    char s3[20] ;
    int len ;

    clrscr( ) ;

    printf ( "\nString s1: %s", s1 ) ;
    len = xstrlen ( s1 ) ;
    printf ( "\nlength of the string s1: %d", len ) ;

    printf ( "\nString s2: %s", s2 ) ;

    xstrcpy ( s3, s1 ) ;
    printf ( "\nString s3 after copying s1 to it: %s", s3 ) ;

    xstrcat ( s3, s2 ) ;
    printf ( "\nString s3 after concatenation: %s", s3 ) ;

    if ( xstrcmp ( s1, s2 ) == 0 )
        printf ( "\nThe strings s1 and s2 are similar" ) ;
    else
        printf ( "\nThe strings s1 and s2 are not similar" ) ;

    getch( ) ;
}

/* finds the length of the string */
int xstrlen ( char *s )
{
    int l = 0 ;
    while ( *s )
    {
        l++ ;
        s++ ;
    }
    return l ;
}

/* copies source string s to the target string t */
void xstrcpy ( char *t, char *s )
{
    while ( *s )
    {
        *t = *s ;
        t++ ;
        s++ ;
    }
    *t = '\0' ;
}

/* concatenates the two strings */
void xstrcat ( char *t, char *s )
{
    while ( *t )
        t++ ;
    while ( *s )
        *t++ = *s++ ;
    *t = '\0' ;
}

/* compares two strings s and t for equality */
int xstrcmp ( char *s, char *t )
{
    while ( *s == *t )
    {
        if ( ! ( *s ) )
            return 0 ;
        s++ ;
        t++ ;
    }
    return ( *s - *t ) ;
}