Add or Concatenate Two Strings

1#include <stdio.h>
2
3int main() {
4    char str1[100] = "Hello ";
5    char str2[] = "World!";
6    
7    int i = 0, j = 0;
8    
9    // Find end of str1
10    while (str1[i] != '\0') i++;
11    
12    // Copy str2 to end of str1
13    while (str2[j] != '\0') {
14        str1[i] = str2[j];
15        i++;
16        j++;
17    }
18    str1[i] = '\0';  // Null terminate
19    
20    printf("Concatenated: %s\n", str1);
21    return 0;
22}