C program to check whether a number is perfect or not

What is a perfect number?
If the sum of the divisor(excluding itself) of a number is equals to the same number, then it is a perfect number.

Example: 6 => 1, 2, 3 are the positive divisors of 6.
1 + 2 + 3 = 6.  Sum of positive divisor gives the same number.  So, 6 is a perfect number.


Write a C program to check whether the given number is perfect or not.

  #include <stdio.h>
  int main () {
        int data, i, res = 0;

        /* get the input from the user */
        printf("Enter your input value:");
        scanf("%d", &data);


        /* check whether the given input is perfect no or not */
        for (i = 1; i <= data/2; i++) {
                if (data % i == 0) {
                        res = res + i;
                }
        }

        /* print the result*/
        if (res == data)
                printf("%d is a perfect number\n", data);
        else
                printf("%d is not a perfect number\n", data);

        return 0;
  }

  Output:

  jp@jp-VirtualBox:~/$ ./a.out
  Enter your input value:6
  6 is a perfect number

  jp@jp-VirtualBox:~/$ ./a.out
  Enter your input value:7
  7 is not a perfect number