c program to concat two string without using concat function

This program helps you to concat two string without using strcat() which is declared in string.h header file in c.

#include <stdio.h>

int main()

{

    char s1[100], s2[100], i, j;

    printf("Enter first string: ");

    scanf("%s", s1);

    printf("Enter second string: ");

    scanf("%s", s2);

    // calculate the length of string s1

    // and store it in i

    for(i = 0; s1[i] != '\0'; ++i);

    for(j = 0; s2[j] != '\0'; ++j, ++i)

    {

        s1[i] = s2[j];

    }

    s1[i] = '\0';

    printf("After concatenation: %s", s1);

    return 0;

}