C Program to Compare Two Strings Without Using strcmp

This C program is used to compare two strings without using strcmp function.

Program:

#include<stdio.h>

#include<string.h>
int cmpstr(char s1[10], char s2[10]);

  int main() {
    char arr1[10] = "Nodalo";
    char arr2[10] = "nodalo";
    printf(" %d", cmpstr(arr1, arr2));
    //cmpstr() is equivalent of strcmp()
    return 0;
    }/
    /s1, s2 are strings to be compared
    int cmpstr(char s1[10], char s2[10]) {
    //strlen function returns the length of argument string passed
    int i = strlen(s1);
    int k = strlen(s2);
    int bigger;
    if (i < k) {
      bigger = k;
    }
    else if (i > k) {
      bigger = i;
    }
    else {
      bigger = i;
    }
    //loops 'bigger' times
    for (i = 0; i < bigger; i++) {
      //if ascii values of characters s1[i], s2[i] are equal do nothing
      if (s1[i] == s2[i]) {
      }
      //else return the ascii difference
      else {
        return (s1[i] - s2[i]);
      }
    }
    //return 0 when both strings are same
    //This statement is executed only when both strings are equal
    return (0);
  }

Program Output:

-32

Explanation:

cmpstr() is a function that illustrates C standard function strcmp(). Strings to be compared are sent as arguments to cmpstr().

Each character in string1 is compared to its corresponding character in string2. Once the loop encounters a differing character in the strings, it would return the ASCII difference of the different characters and exit.