Tukukkk

i was wondering what can I do to prompt an error when I input a negative number. I used a for loop for this program. What this program does, or at least its supposed to do, is to output the factor of any given number (if positive). But I am not sure how to make my code to prompt an error or at least keep asking for a number if the number that input is less or equal to 0.

I used the variable n as the number to input by the user.

I am really new to programming and I am eager to finish this program as soon as possible. Can you please assist?

  #include <iostream>

  #include <math.h>

  #include <stdlib.h>

  using namespace std;





int main()

{

double n;

cout << "Welcome to this program... Hope you like it" << flush << endl;

do

{

    int i, fact = 1, n;

    cout << "Please enter a value for the variable " "n: ";

    cin >> n;



    for (i = 1; i <= n; i++) {

        fact = fact * i;

    }

    cout << "Factorial of " << n << " is: " << fact << endl;

    cout << " Thanks for using this program... hope you liked it!" << endl;

} while (n >= 0);

return 0;

}

Commens in the code:

#include <iostream>



// it's best not to do using namespace std. It's a huge namespace



int main()

{

    std::cout << "Welcome to this program... Hope you like itn";

    do

    {

        int i, fact = 1, n;

        std::cout << "Please enter a value for the variable " "n: ";

        std::cin >> n;



        // if std::cin is in a failed state then break out of the loop.

        if (std::cin.fail()) break;



        // added check if n<0. if n<0 ptint error on stderr

        if (n<0) {

            std::clog << "Error: you must supply a number equal to or greater than zeron";

        } else { // if n>=0 

            for (i = 1; i <= n; i++) {

                fact = fact * i;

            }

            std::cout << "Factorial of " << n << " is: " << fact << "n";

        }

    } while (true); // <- now always true 



    std::cout << "nThanks for using this program... hope you liked it!n";

    return 0;

}