C program to insert character into the string at the given location

Write a C program to insert character into the string at the given location.

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

  int main() {
        char mystr[256], output[256];
        int ch, pos, i = 0, j = 0;

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

        /* get the input character to insert */
        printf("Enter the character to insert:");
        ch = getchar();

        /* get the location to insert the i/p character */
        printf("Enter the location(0-%d):", strlen(mystr));
        scanf("%d", &pos);

        /* boundary check */
        if (pos < 0 || pos > strlen(mystr)) {
                printf("Boundary Value Exceeded!!!\n");
                return 0;
        }

        /* copying characters present before the given location */
        while (i < pos) {
                output[j++] = mystr[i];
                i++;
        }

        /* copying the input character at the given location */
        output[j++] = ch;

        /* copying the left characters */

        while (mystr[i] != '\0') {

                output[j++] = mystr[i];

                i++;

        }

        output[j] = '\0';

        /* print the resultant string */

        printf("Resultant String: %s\n", output);

        return 0;

  }

  Output:

  jp@jp-VirtualBox:~/$ ./a.out
  Enter your input string:helo world
  Enter the character to insert:l
  Enter the location(0-10):3
  Resultant String: hello world