Loop Practice

Video Summary: https://youtu.be/KFHVBWSCbQw

Consider this solution to a prior exercise, which rolled two dice and declared a winner, if there was one, between the two:

Modify the program so that it uses a loop to keep playing.

At the end of each roll, prompt the user asking if they would like to play again, and to enter 'y' if yes, 'n' if no
Check if the user input 'y', 'n', or something else
If 'y', roll again. If 'n', end the program. If something else, prompt the user again without rolling the dice

When you are finished, your output might look like this:

Player one rolled 3
Player two rolled 5
Player two wins!
Would you like to roll again? Enter y for yes or n for no
y
Player one rolled 2
Player two rolled 3
Player two wins!
Would you like to roll again? Enter y for yes or n for no
a
You must enter y for yes or n for no
n
The game has ended

Solution

/*
Program name: diceroll.cpp
Author: Devon Blewett
Purpose: This program generates two random numbers between 1 and 6 and declares a winner between them, unless there is a draw

If the user enters y, it will loop.  If the user enters n, it will stop.  If the user enters something else, they will be prompted for correct input.

Written for the Open Textbooks program
*/
#include <iostream>
#include <time.h>
#include <string.h>
using namespace std;

int main(){
// Variable for user's choice to keep playing
// This could have been a char as well, but string will handle multiple letters when evaluating bad input
    string choice = "";
// Start the loop, and run until user enters 'n' or 'N'
// Checking the capital isn't required, but is good practice
    while(choice != "n" && choice != "N")
    {
// the values need to be assigned within the loop, or the rolls would never change
        srand(time(NULL));
        int dice1 = rand() % 6 + 1;
        int dice2 = rand() % 6 + 1;

cout << "Player one rolled " << dice1 << endl;
        cout << "Player two rolled " << dice2 << endl;
// player ones roll is higher
        if(dice1 > dice2){
            cout << "Player one wins!" << endl;
        }
// the players rolls are the same
        else if(dice1 == dice2){
            cout << "The players draw." << endl;
        }
// since there is only one more outcome, you do not need to check a condition here
        else{
            cout << "Player two wins!" << endl;
            }
        
        cout << "Would you like to roll again? Enter y for yes or n for no" << endl;
        cin >> choice;
// if the user entered bad input, prompt them again without the program advancing
        while(choice != "y" && choice != "Y" 
            && choice != "n" && choice != "N")
        {
            cout << "You must enter y for yes or n for no" << endl;
            cin >> choice;
        } 
    }
// When the user enters n, they will end up here
    cout << "The game has ended" << endl;
	return 0;
}

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