C++

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Improve tic-tac-toe game

Victor89 (62)
My following code plays a tic tac toe game vs computer, where the computer is making random moves.

I am trying to modify the application so that I can choose who is going to make the first move, me or the computer, but I still haven't found a way.

Help will be greatly appreciated!

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#include "stdafx.h"
#include <iostream>

using namespace std;

char player = 'X';
char computer = 'O';

char board[3][3] =
	{ 
	  {'1', '2', '3'},
	  {'4', '5', '6'},
	  {'7', '8', '9'},
	};



void Instructions()
{
	cout << "1 - Easy Game\n";
	cout << "2 - Quit Game\n";
}

void Draw()
{
	system("cls");
	cout <<"\tWelcome to Tic Tac Toe 2.0\n";

	for(int i=0; i<3; i++)
	{
		for(int j=0; j<3; j++)
		{
			cout << board[i][j] << " ";
		}
		cout << endl;
	}
}

void Input()
{
	int a;
	cin >> a;

	if(a == 1) 
		if(board[0][0] == '1')
			board[0][0] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}

	else if(a == 2) 
		if(board[0][1] == '2')
			board[0][1] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}
	else if(a == 3) 
		if(board[0][2] == '3')
			board[0][2] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}
	else if(a == 4) 
		if(board[1][0] == '4')
			board[1][0] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}
	else if(a == 5) 
		if(board[1][1] == '5')
			board[1][1] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}
		else if(a == 6) 
		if(board[1][2] == '6')
			board[1][2] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}
		else if(a == 7) 
		if(board[2][0] == '7')
			board[2][0] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}
		else if(a == 8) 
		if(board[2][1] == '8')
			board[2][1] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}
		else if(a == 9) 
		if(board[2][2] == '9')
		   board[2][2] = player;
		else
		{
			cout << "Field already taken, please try again." << endl <<endl;
			Input();
		}
}

int ComputerEasy()
{
	int i, j;
	bool found = false;
	while (found == false)
	{

		i = rand() % 3;
		j = rand() % 3;
		if(board[i][j] != player && board[i][j] != computer)
			{			
				return board[i][j] = computer;
				found = true;
			}
	}
}

char ToggleComputer()
{
	if(player == 'X')
		return computer = 'O';

	else if(player == 'O')
		return computer = 'X';
}

int CheckWin()
{
	
	if(board[0][0] == 'X' && board[0][1] == 'X' && board[0][2] == 'X')
		return 'X';
	if(board[1][0] == 'X' && board[1][1] == 'X' && board[1][2] == 'X')
		return 'X';
	if(board[2][0] == 'X' && board[2][1] == 'X' && board[2][2] == 'X')
		return 'X';
	
	
	if(board[0][0] == 'X' && board[1][0] == 'X' && board[2][0] == 'X')
		return 'X';
	if(board[0][1] == 'X' && board[1][1] == 'X' && board[2][1] == 'X')
		return 'X';
	if(board[0][2] == 'X' && board[1][2] == 'X' && board[2][2] == 'X')
		return 'X';

	//diagonals
	if(board[0][0] == 'X' && board[1][1] == 'X' && board[2][2] == 'X')
		return 'X';
	if(board[0][2] == 'X' && board[1][1] == 'X' && board[2][0] == 'X')
		return 'X';
		
	if(board[0][0] == 'O' && board[0][1] == 'O' && board[0][2] == 'O')
		return 'O';
	if(board[1][0] == 'O' && board[1][1] == 'O' && board[1][2] == 'O')
		return 'O';
	if(board[2][0] == 'O' && board[2][1] == 'O' && board[2][2] == 'O')
		return 'O';
	

	if(board[0][0] == 'O' && board[1][0] == 'O' && board[2][0] == 'O')
		return 'O';
	if(board[0][1] == 'O' && board[1][1] == 'X' && board[2][1] == 'O')
		return 'O';
	if(board[0][2] == 'O' && board[1][2] == 'O' && board[2][2] == 'O')
		return 'O';

	//diagonals
	if(board[0][0] == 'O' && board[1][1] == 'O' && board[2][2] == 'O')
		return 'O';
	if(board[0][2] == 'O' && board[1][1] == 'O' && board[2][0] == 'O')
		return 'X';

	return '/';	
}

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

	int choice;
	cin >> choice;

	Draw();

	while(choice == 1)
	{
		int moves = 0;
		moves++;
		Draw();
		Input();
		
		if (CheckWin() == 'X')
		{
			Draw();
			cout << "Player X won!";
			break;
		}
		else if(CheckWin() == 'O')
		{
			Draw();
			cout << "Player O won!";
			break;
		}
		else if (moves == 9)
		{
			Draw();
			cout <<" It's a draw!";
			break;
		}
		ComputerEasy();
		ToggleComputer();
	}

	system("pause");
}
Last edited on
squished18 (64)
bool user_goes_first;

from user input, set user_goes_first appropriately

line 209:
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if (user_goes_first)
   Input();
else
   user_goes_first = true;


So the first time through, if the computer is supposed to go first, Input() is skipped and goes to the computer taking a turn.
Victor89 (62)
Thank you for your answer, but still I have an issue as it keeps asking over and over again the question "Will you go first?". I don't know how to make it ask only the first time. Also the first move must always be an 'X'.

Here is my updated code and I will explain it a little more :

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#include "stdafx.h"
#include <iostream>
#include <string>
using namespace std;

char board[3][3] =
	{ 
	  {'1', '2', '3'},
	  {'4', '5', '6'},
	  {'7', '8', '9'},
	};

char player = 'X';
char computer = 'O';
void Instructions()
{
	cout << "1 - Easy Game\n";
	cout << "2 - Quit Game\n";
}

void Draw()
{
	system("cls");
	cout <<"\tWelcome to Tic Tac Toe 2.0\n";

	for(int i=0; i<3; i++)
	{
		for(int j=0; j<3; j++)
		{
			cout << board[i][j] << " ";
		}
		cout << endl;
	}
}

char askYesNo(string question)
{
	char response;
	do
	{
		cout << question << "y/n";
		cin >> response;
	} while (response != 'y' && response != 'n');

	return response;
}

void Input()
{
	int a;
	cin >> a;

	if(a == 1) 
		if(board[0][0] == '1')
			board[0][0] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}

	else if(a == 2) 
		if(board[0][1] == '2')
			board[0][1] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}
	else if(a == 3) 
		if(board[0][2] == '3')
			board[0][2] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}
	else if(a == 4) 
		if(board[1][0] == '4')
			board[1][0] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}
	else if(a == 5) 
		if(board[1][1] == '5')
			board[1][1] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}
		else if(a == 6) 
		if(board[1][2] == '6')
			board[1][2] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}
		else if(a == 7) 
		if(board[2][0] == '7')
			board[2][0] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}
		else if(a == 8) 
		if(board[2][1] == '8')
			board[2][1] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}
		else if(a == 9) 
		if(board[2][2] == '9')
		   board[2][2] = player;
		else
		{
			cout << "Field already taken, please try again." << endl <<endl;
			Input();
		}
}

int ComputerEasy()
{
	int i, j;
	bool found = false;
	while (found == false)
	{

		i = rand() % 3;
		j = rand() % 3;
		if(board[i][j] != player && board[i][j] != computer)
			{			
				return board[i][j] = computer;
				found = true;
			}
	}
}

char ToggleComputer()
{
	if(player == 'X')
		return computer = 'O';

	else if(player == 'O')
		return computer = 'X';
}

char UserGoFirst()
{
	char go_first = askYesNo("Will you go first?");
	if (go_first == 'y')
	{
		cout << "Make your move.\n";
		return 'X';
	}
	if 	(go_first == 'n')
	{
		cout <<"I will go first.";
		return 'O';
	}
}

int CheckWin()
{
	
	if(board[0][0] == 'X' && board[0][1] == 'X' && board[0][2] == 'X')
		return 'X';
	if(board[1][0] == 'X' && board[1][1] == 'X' && board[1][2] == 'X')
		return 'X';
	if(board[2][0] == 'X' && board[2][1] == 'X' && board[2][2] == 'X')
		return 'X';
	
	
	if(board[0][0] == 'X' && board[1][0] == 'X' && board[2][0] == 'X')
		return 'X';
	if(board[0][1] == 'X' && board[1][1] == 'X' && board[2][1] == 'X')
		return 'X';
	if(board[0][2] == 'X' && board[1][2] == 'X' && board[2][2] == 'X')
		return 'X';

	//diagonals
	if(board[0][0] == 'X' && board[1][1] == 'X' && board[2][2] == 'X')
		return 'X';
	if(board[0][2] == 'X' && board[1][1] == 'X' && board[2][0] == 'X')
		return 'X';
		
	if(board[0][0] == 'O' && board[0][1] == 'O' && board[0][2] == 'O')
		return 'O';
	if(board[1][0] == 'O' && board[1][1] == 'O' && board[1][2] == 'O')
		return 'O';
	if(board[2][0] == 'O' && board[2][1] == 'O' && board[2][2] == 'O')
		return 'O';
	

	if(board[0][0] == 'O' && board[1][0] == 'O' && board[2][0] == 'O')
		return 'O';
	if(board[0][1] == 'O' && board[1][1] == 'X' && board[2][1] == 'O')
		return 'O';
	if(board[0][2] == 'O' && board[1][2] == 'O' && board[2][2] == 'O')
		return 'O';

	//diagonals
	if(board[0][0] == 'O' && board[1][1] == 'O' && board[2][2] == 'O')
		return 'O';
	if(board[0][2] == 'O' && board[1][1] == 'O' && board[2][0] == 'O')
		return 'X';

	return '/';	
}

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

	int choice;
	cin >> choice;

	Draw();

	while(choice == 1)
	{
		int moves = 0;
		moves++;
		Draw();
		if(UserGoFirst() == 'X')
		{
			Input();
				
		}
		else
		{
			UserGoFirst() == 'O';
		}
		
		Draw();
		if (CheckWin() == 'X')
		{
			Draw();
			cout << "Player X won!";
			break;
		}
		else if(CheckWin() == 'O')
		{
			Draw();
			cout << "Player O won!";
			break;
		}
		else if (moves == 9)
		{
			Draw();
			cout <<" It's a draw!";
			break;
		}
		ComputerEasy();
		ToggleComputer();
	}

	system("pause");
}


I will explain the following functions:

char askYesNo(string question) // asks a question and returns y on n

char UserGoFirst() //return 'X' if the user will go first and 'O if the computer will go first

squished18 (64)
Each iteration of your while loop is for one turn. Right now, you have UserGoFirst inside the while loop. So for every iteration (turn), there will be a prompt to ask which user should go first.

You likely want the UserGoFirst() call outside the while loop.
Victor89 (62)
This is my updated code with the solution for who goes first computer, or player, but always the first one will be an 'X', I am not sure that my solution is a great one, but at least it works as for my previous tries that didn't do what I wanted.

My solution is:
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char response;
	cout << "Do you want to go first? y/n";
	cin >> response;

	if(response == 'y')
	{
		goto user;
	}
	else
	{
		computer = 'X';
		player = 'O';
		goto computer;
	}
	

	while(choice == 1)
	{
		Draw();
		if (CheckWin() == 'X')
		{
			Draw();
			cout << "Player X won!";
			break;
		}
		else if(CheckWin() == 'O')
		{
			Draw();
			cout << "Player O won!";
			break;
		}
		else if (moves == 9)
		{
			Draw();
			cout <<" It's a draw!";
			break;
		}

	computer:
		moves++;
		ComputerEasy();
		Draw();

	user:
		Input();	
		ToggleComputer();

	}



But i still have an issue:

If the board is full that means there were made 9 moves, it won't annonce the winner or the draw (maybe because the game is waiting for another move, but another move will be impossible as the board is full)

Here is the full updated code:

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#include <iostream>
#include <conio.h>
#include <string>
#include <ctime>
using namespace std;

char board[3][3] =
	{ 
	  {'1', '2', '3'},
	  {'4', '5', '6'},
	  {'7', '8', '9'},
	};

char player = 'X';
char computer = 'O';
void Instructions()
{
	cout << "1 - Easy Game\n";
	cout << "2 - Quit Game\n";
}

void Draw()
{
	system("cls");
	cout <<"\tWelcome to Tic Tac Toe 2.0\n";

	for(int i=0; i<3; i++)
	{
		for(int j=0; j<3; j++)
		{
			cout << board[i][j] << " ";
		}
		cout << endl;
	}
}



void Input()
{
	int a;
	cin >> a;

	if(a == 1) 
		if(board[0][0] == '1')
			board[0][0] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}

	else if(a == 2) 
		if(board[0][1] == '2')
			board[0][1] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}
	else if(a == 3) 
		if(board[0][2] == '3')
			board[0][2] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}
	else if(a == 4) 
		if(board[1][0] == '4')
			board[1][0] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}
	else if(a == 5) 
		if(board[1][1] == '5')
			board[1][1] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}
		else if(a == 6) 
		if(board[1][2] == '6')
			board[1][2] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}
		else if(a == 7) 
		if(board[2][0] == '7')
			board[2][0] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}
		else if(a == 8) 
		if(board[2][1] == '8')
			board[2][1] = player;
		else
		{
			cout <<"Field already taken, please try again." << endl <<endl;
			Input();
		}
		else if(a == 9) 
		if(board[2][2] == '9')
		   board[2][2] = player;
		else
		{
			cout << "Field already taken, please try again." << endl <<endl;
			Input();
		}
}

int ComputerEasy()
{
	srand(time(0));
	int i, j;
	bool found = false;
	while (found == false)
	{

		i = rand() % 3;
		j = rand() % 3;
		if(board[i][j] != player && board[i][j] != computer)
			{			
				return board[i][j] = computer;
				found = true;
			}
	}
}

char ToggleComputer()
{
	if(player == 'X')
		return computer = 'O';

	else if(player == 'O')
		return computer = 'X';
}



int CheckWin()
{
	
	if(board[0][0] == 'X' && board[0][1] == 'X' && board[0][2] == 'X')
		return 'X';
	if(board[1][0] == 'X' && board[1][1] == 'X' && board[1][2] == 'X')
		return 'X';
	if(board[2][0] == 'X' && board[2][1] == 'X' && board[2][2] == 'X')
		return 'X';
	
	
	if(board[0][0] == 'X' && board[1][0] == 'X' && board[2][0] == 'X')
		return 'X';
	if(board[0][1] == 'X' && board[1][1] == 'X' && board[2][1] == 'X')
		return 'X';
	if(board[0][2] == 'X' && board[1][2] == 'X' && board[2][2] == 'X')
		return 'X';

	//diagonals
	if(board[0][0] == 'X' && board[1][1] == 'X' && board[2][2] == 'X')
		return 'X';
	if(board[0][2] == 'X' && board[1][1] == 'X' && board[2][0] == 'X')
		return 'X';
		
	if(board[0][0] == 'O' && board[0][1] == 'O' && board[0][2] == 'O')
		return 'O';
	if(board[1][0] == 'O' && board[1][1] == 'O' && board[1][2] == 'O')
		return 'O';
	if(board[2][0] == 'O' && board[2][1] == 'O' && board[2][2] == 'O')
		return 'O';
	

	if(board[0][0] == 'O' && board[1][0] == 'O' && board[2][0] == 'O')
		return 'O';
	if(board[0][1] == 'O' && board[1][1] == 'X' && board[2][1] == 'O')
		return 'O';
	if(board[0][2] == 'O' && board[1][2] == 'O' && board[2][2] == 'O')
		return 'O';

	//diagonals
	if(board[0][0] == 'O' && board[1][1] == 'O' && board[2][2] == 'O')
		return 'O';
	if(board[0][2] == 'O' && board[1][1] == 'O' && board[2][0] == 'O')
		return 'X';

	return '/';	
}

int main()
{
	int moves = 0;
	cout << endl;
	Instructions();

	int choice;
	cin >> choice;

	Draw();

	char response;
	cout << "Do you want to go first? y/n";
	cin >> response;

	if(response == 'y')
	{
		goto user;
	}
	else
	{
		computer = 'X';
		player = 'O';
		goto computer;
	}
	

	while(choice == 1)
	{
		Draw();
		if (CheckWin() == 'X')
		{
			Draw();
			cout << "Player X won!";
			break;
		}
		else if(CheckWin() == 'O')
		{
			Draw();
			cout << "Player O won!";
			break;
		}
		else if (moves == 9)
		{
			Draw();
			cout <<" It's a draw!";
			break;
		}

	computer:
		moves++;
		ComputerEasy();
		Draw();

	user:
		Input();	
		ToggleComputer();

	}
	getch();
}
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