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Basic
Switch Case
Goto
Operators
if Statement
Nested if
While Loop
For Loop
Array
2D Array
Patterns
Excersises
Others



C Program to Find if the Given Number is Perfect Number or Not


The following example shows, find whether a number is a perfect number.

  • Takes an integer input from the user.
  • Loops from 1 to one less than the number to find proper divisors.
  • Calculates the sum of all proper divisors of the number.
  • Checks if the sum equals the number to determine if it's a perfect number.

Example : pgm.c

#include <stdio.h>

int main() {
    int num, sum = 0;

    // Input a number
    printf("Enter a number: ");
    scanf("%d", &num);

    // Find sum of proper divisors
    for (int i = 1; i < num; i++) {
        if (num % i == 0) {
            sum += i;
        }
    }

    // Check if the number is perfect
    if (sum == num) {
        printf("%d is a Perfect Number.\n", num);
    } else {
        printf("%d is not a Perfect Number.\n", num);
    }

    return 0;
}

Output:

Enter a number: 6
6 is a Perfect Number.