// References to other code that I can use here
#include "stdafx.h"
#include <iostream>
#include <string>

using namespace std; // So I don't have to keep typing std:: before everything

bool is_digits(const string &str) // A boolean true or false function I create, with the parameter of a string (text)
{
    // Does the string only contain characters the teacher wants?
    return str.find_first_not_of("0123456789") == string::npos; // If so, return true. Otherwise return false
}

int _tmain(int argc, _TCHAR* argv[]) // This function/method gets run as soon as the program starts
{
    string sNums; // Variable to hold the string they enter
    bool isValid; // Whether or not the string they've entered is a valid positive integer

    do { // Do the following code until the condition next to (while) is false
        cout << "Enter a positive integer: "; // Ask for a string (text) from the user
        getline(cin, sNums); // Get the string and store it into our variable (sNums)
        cout << endl; // Display everything after this on a new line

        isValid = sNums.length() && is_digits(sNums); // Set our boolean (true or false) variable to the result (return value) of our is_digits function

        if (!isValid) { // If the entered string is not (!) valid, then do this:
            cout << "That is not a valid integer. Please try again." << endl << endl; // Tell them it's not valid and put two blank lines there
        }
    } while (!isValid); // While !isValid [in other words, while the entered string is not (denoted by exclamation point) valid], ask for a new string

    int iCurrInt, iSum = 0, iProduct = 1; // Create three new integer variables to store our desired output

    cout << "Will parse these integers: "; //Output that we will list the integers back

    for (int i = 0, l = sNums.length(); i < l; i++) { // Loop through the characters (numbers) in the string
        iCurrInt = sNums[i] - '0'; // Complicated to explain, but this will change the character into an integer we can use and store the new value

        cout << iCurrInt << " "; // Output the character and then a space

        iSum += iCurrInt; // Increment our iSum variable by the value of our current integer variable and then store it back into iSum
        iProduct *= iCurrInt; // Multiple our iProduct value by the value of our current integer variable and then store it back into iProduct
    }

    cout << endl; // Output an end-of-line character

    cout << "Sum of the given integers: " << iSum << endl; // Output text, then the sum, then an end-of-line character
    cout << "Product of given integers: " << iProduct << endl << endl; // Output text, then the product, then two end-of-line characters

    system("pause"); // Wait for the user to press a key before finishing the program and closing it
}