60: ***(Syntax)*** Write a program in C++ to find the perfect numbers between the user-defined range.


// Write a program in C++ to find the perfect numbers between the user-defined range.
// The perfect numbers between 1 to 500 are:
// 6
// 28
// 496
// **************************************************************************************************

#include <iostream>
using namespace std;
int main()
{

    int start, end;
    cout << "\nEnter the starting number of range: ";
    cin >> start;
    cout << "Enter the ending number of range: ";
    cin >> end;

    cout << "\n*********************************************************************************\n\n";

    int sum;
    for (int i = start; i <= end; i++)
    {
        sum = 0;
        for (int j = 1; j < i; j++)
        {
            if (i % j == 0)
            {
                sum = sum + j;
            }
        }
        if (sum==i)
        {
            cout << i << ' ';
        }
       
    }

    return 0;
}

Note:

  1.     In this code, if you do not write sum = 0 within the loop, this loop won't work. Because, sum must be zero, every time the loop resets.
  2.      If you write j <= i in place of j < i , compiler will also take the number itself as its multiple and the sum of multiples will never be equal to number.


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