//
//  using_strings.c
//  
//
//  Created by Bibhas Ghoshal on 20/02/21.
//

#include <stdio.h>

int strlen (const char *s) {
    int n;
    for (n=0; *s!='\0'; ++s)
        ++n;
    return n;
}

char *strcat(char *s1, const char *s2)
{
    char *p = s1;
    while (*p != '\0') /* go to end */
        ++p;
    while(*s2 != '\0')
        *p++ = *s2++; /* copy */ *p = '\0';
    return s1;
}


int strcmp(char *s1, const char *s2) {
    for (;*s1!='\0'&&*s2!='\0'; s1++,s2++) {
        if (*s1>*s2) return 1;
         if (*s2>*s1) return -1;
        
    }
    if (*s1 != '\0') return 1;
    if (*s2 != '\0') return -1;
    return 0;
}

char * strcpy (char *s1, const char *s2) {
    char *p = s1;
    while (*p++ = *s2++) ;
    return s1;
}
    
    
int main()
{
    char s1[ ] = "beautiful big sky country",
    s2[ ] = "how now brown cow"; printf("%d\n",strlen (s1));
    printf("%d\n",strlen (s2+8));
    printf("%d\n", strcmp(s1,s2));
    printf("%s\n",s1+10);
    strcpy(s1+10,s2+8);
    strcat(s1,"s!");
    printf("%s\n", s1);
    return 0;
}