Sentinel Value Demonstration

// This program demonstrates the usage of
// a sentinel value to create a continuous loop
// that can be exited based on a user input.

#include <iostream>

using namespace std;

int main()
{
    int numInput;       // Just a simple number input.
    char userInput = '.';   // Assign a sentinel character.
                // This character is important, as
                // it will be used to check if the user
                // is finished with the program based
                // on the condition.

    while(userInput != 'q')     // If userInput is NOT q... execute the loop.
    {
        // Body of content. This can be anything you want it to be.
        // This will get repeated numerous times until the input 'q' is
        // given, which will break the while loop condition.

        cout << "Enter a whole value: " << endl;
        cin >> numInput;
        cout << "The square value of that is " << numInput * numInput << endl;

        // This is the part where the user gets the opportunity to exit
        // the loop.
        cout << "Enter another number? Type 'q' to quit." << endl;
        cin >> userInput;
    }

    // When you're here, you have exited the loop.
    // End program.
    return 0;
}