Question

Write a C++ program to print all the perfect numbers below a certain given number. A perfect number is a number that that is equal to the sum of it's divisors other than itself . For example, 6 and 28 are all perfect numbers.

6 = ( 1+2 +3)

28 = (1+2+4+7+14)

Make sure your program conforms to the following requirements:

1. Accept the upper limit from the user (as an integer). (5 points)
2. Make sure the number is positive (at least 1). (5 points).
3. Go from 1 to to the upper limit and print all numbers that are perfect. (35 points)
4. Add comments wherever necessary. (5 points)

Sample Runs:

NOTE: not all possible runs are shown below.

Sample Run 1

Welcome to the locate perfect numbers program...
What is the upper value?30
The following are perfect numbers...
6
28

Process finished with exit code 0

Sample Run 2

Welcome to the locate perfect numbers program...
What is the upper value?-8
What is the upper value? (must be an integer > 0)0
What is the upper value? (must be an integer > 0)500
The following are perfect numbers...
6
28
496

General Requirements:
1. No global variables (variables outside of main() )

2.Please try and restrict yourself to input/output statements, variables, selection statements and loops. Using any other concept (like functions or arrays) will result in loss of points.

3. All input and output must be done with streams, using the library iostream

4. You may only use the cmath, iostream, and iomanip libraries (you do not need any others for these tasks)

5. NO C style printing is permitted. (Aka, don’t use printf). Use cout if you need to print to the screen.

6. When you write source code, it should be readable and well-documented (comments).

Answer 1

// do comment if any problem arises

//code

#include <iostream>

#include <fstream>

using namespace std;

int main()

{

    int upper_value;

    // welcome message

    cout << "Welcome to the locate perfect numbers program...\n";

    cout << "What is the upper value?";

    // read upper value from user

    cin >> upper_value;

    // read upper value till user enters positive number

    while (upper_value <= 0)

    {

        cout << "What is the upper value? (must be an integer > 0)";

        cin >> upper_value;

    }

    cout << "The following are perfect numbers...\n";

    for (int number = 1; number <= upper_value; number++)

    {

        int sum = 0;

        // calculate sum of its devisors

        for (int j = 1; j < number; j++)

        {

            if (number % j == 0)

                sum += j;

        }

        // if sum is equal to number itself then number is perfect

        if (sum == number)

            cout << number << endl;

    }

}

Output: