Perfect number

A number is called perfect if the number is equal to the sum of its divisors (the number itself is not considered a divisor in this case).

Check Perfect Number

#include <iostream>
using namespace std;

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

    cout << "Enter a number to check for perfect: ";
    cin >> number;

    for (int i = 1; i < number; i++) {
        if (number % i == 0) {
            sum = sum + i;
        }
    }

    if (sum == number) {
        cout << number << " is a perfect number";
    }
    else {
        cout << number << " is not a perfect number";
    }

    return 0;
}

Output

Enter a number to check for perfect: 28
28 is a perfect number

Perfect Number List (1-n)

#include <iostream>
using namespace std;

void checkPerfect(int max) {
    int number, min = 1, i, sum = 0;

    for (number = min; number <= max; number++) {
        sum = 0;
        for (i = 1; i < number; i++) {
            if (number % i == 0) {
                sum = sum + i;
            }
        }
        if (sum == number) {
            cout << number << " is a perfect number" << endl;
        }
    }
}

int main() {
    int max;

    cout << "Enter the upper bound to find perfect numbers: ";
    cin >> max;

    checkPerfect(max);

    return 0;
}

Output

Enter the upper bound to find perfect numbers: 10000
6 is a perfect number
28 is a perfect number
496 is a perfect number
8128 is a perfect number