A version of the 21 game without proper error checking or rule checking.

21game.cpp

#include <stdio.h>
#include <iostream>

using namespace std;

const char * welcometext =
"Welcome to the game of 21! \n\
Rules: \n\
First choose who goes first, the game starts with 21 sticks in\n\
a pile, the player forced to take the last stick loses. \n\
At each turn, you can remove up to 3 sticks.";

const char * player1Turn = "It is player 1's turn";
const char * player2Turn = "It is player 2's turn";

const char * player1Win = "Player 1 wins!";
const char * player2Win = "Player 2 wins!";

const char * sticksLeftPrefixText = "There are ";
const char * sticksLeftSuffixText = " sticks left";

int main(){
	cout << welcometext << endl;

	int sticks = 21;
	int currentPlayer = 1;
	int continuePlaying = true;
	int sticksToTake = 0;

	while(continuePlaying){		
		cout << sticksLeftPrefixText << sticks << sticksLeftSuffixText << endl;
		cout << (currentPlayer % 2 == 0 ? player1Turn : player2Turn) << endl;
		
		cin >> sticksToTake;
		sticks = sticks - sticksToTake;	
		if(sticks <= 0){
			continuePlaying = false;
		}
		currentPlayer++;
	}

	cout << (currentPlayer % 2 == 0 ? player1Win : player2Win) << endl;


}