C program to concatenate two strings using pointers

Write a C program to concatenate two strings using pointers.

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

  int main() {
        char str1[256], str2[256], *res;
        int i, j, len;

        /* get the first input string from the user */
        printf("Enter your first input string:");
        fgets(str1, 256, stdin);
        str1[strlen(str1) - 1] = '\0';

        /* get the secon input string from the user */
        printf("Enter your second input string:");
        fgets(str2, 256, stdin);
        str2[strlen(str2) - 1] = '\0';

        /*
         * length of concatenated string is equal
         * to the sum of lengths of given input strings
         */
        len = strlen(str1) + strlen(str2);

        /* dynamically allocate memory for output string */
        res = (char *) malloc(sizeof(char) * len);

        /* concatenates input strings and stores the output in res */
        for (i = 0; i < strlen(str1); i++) {
                *(res + i) = *(str1 + i);
        }

        for (j = 0; j <= strlen(str2); i++, j++) {
                *(res + i) = *(str2 + j);
        }

        /* print the result */

        printf("Result:\n");

        printf("String 1: %s\n", str1);

        printf("String 2: %s\n", str2);

        printf("Output   : %s\n", res);

        return 0;

  }

  Output:

  jp@jp-VirtualBox:~/$ ./a.out
  Enter your first input string:India 
  Enter your second input string:Today
  Result:
  String 1: India
  String 2: Today
  Output   : IndiaToday