My Tic-Tac-Toe - Advice/Tips?

[kevinmur]

Hi guys,

I'm just new to C++ for the last 4 days. Could you offer any tips and advice about things I've done in the below program?

I know the following:
vector (a little bit - more like a resizeable array)
array
standard input/output
if, while and for loops
how to sorta create a function (it seems to work at least)

so I thought I'd learn better from practise and people suggested to try tic-tac-toe with what I know.

Check it:

#include <iostream>
#include <string>
#include <vector>
#include <ctime>
#include <algorithm>
#include <cctype>

using namespace std;

//set up moves list
vector<string> moves;
vector<string>::iterator iter;
     
//set up board
const int ROWS = 3;
const int COLS = 3;
char board[ROWS][COLS] = {
{'-','-','-'},
{'-','-','-'},
{'-','-','-'}};

//test if board is full
bool full_board(char full)
{
     for (int i = 0; i < ROWS; ++i)
     {
         for (int j = 0; j < COLS; ++j)
             if (board[i][j] == full)
             return false;
     }
     return true;
}

//test if someone wins     
bool winner(char user)
{
 //EVERY POSSIBEL WINNING COMBINATION!
   while ((board[0][0] == user) &&
          (board[0][1] == user) && 
          (board[0][2] == user)){
          return true;};
   
   while ((board[1][0] == user) &&
          (board[1][1] == user) && 
          (board[1][2] == user)){
          return true;};
   
   while ((board[2][0] == user) &&
          (board[2][1] == user) && 
          (board[2][2] == user)){
          return true;};
   
   while ((board[0][0] == user) &&
          (board[1][0] == user) && 
          (board[2][0] == user)){
          return true;};
   
   while ((board[0][1] == user) &&
          (board[1][1] == user) && 
          (board[2][1] == user)){
          return true;};
   
   while ((board[0][2] == user) &&
          (board[1][2] == user) && 
          (board[2][2] == user)){
          return true;};
   
   while ((board[0][0] == user) &&
          (board[1][1] == user) && 
          (board[2][2] == user)){
          return true;};
   
   while ((board[2][0] == user) &&
          (board[1][1] == user) && 
          (board[0][2] == user)){
          return true;};
   return false;
}

//test if user has made an OK move
bool user_move_ok(string move)
{
     for (iter = moves.begin(); iter < moves.end(); ++iter)
     {
         if (*iter == move)
         {
            moves.erase(iter);
            return true;
         }
     }
     cout << "That's not a valid move.";
     return false;
}

//make the computers' move
string comp_move()
{
     srand(time(0));
     random_shuffle(moves.begin(), moves.end()); 
     string compMove = moves[0];
     moves.erase(moves.begin());
     return compMove;  
}

//play the game!
void play()
{
     //list available moves (initializes for new game)
     moves.push_back("1,1");
     moves.push_back("1,2");
     moves.push_back("1,3");
     moves.push_back("2,1");
     moves.push_back("2,2");
     moves.push_back("2,3");
     moves.push_back("3,1");
     moves.push_back("3,2");
     moves.push_back("3,3");
     //-----------------------------------------------------------     
     //GAME LOOP BEGINS
     do
     {
     //display board
     for (int i = 0; i < ROWS; ++i)
     {
         cout << "\t\t\t";
         for (int j = 0; j < COLS; ++j)
         cout << " " << board[i][j];
     cout << endl;
     }
     
     string userMove;
     do
     {
     //prompt for input
     cout << "\nYour move (ROW,COL): ";
     cin >> userMove;
     
     //ensure input is valid
     }
     while (!user_move_ok(userMove));
     
     //break down moves to array co-ordinates
     //users' move
     string userStrRow = userMove.substr(0,1);
     string userStrCol = userMove.substr(2,1);
     int userIntRow = atoi(userStrRow.c_str());
     int userIntCol = atoi(userStrCol.c_str());
     
     //put the moves in the array
     //users'
     board[userIntRow-1][userIntCol-1] = 'X';
     
     //check if user wins or board is full
     if (winner('X'))
        break;
     if (full_board('-'))
        break;
     //get computer move
     string computer = comp_move();
     
     //break down moves to array co-ordinates
     //computers' move
     string compStrRow = computer.substr(0,1);
     string compStrCol = computer.substr(2,1);
     int compIntRow = atoi(compStrRow.c_str());
     int compIntCol = atoi(compStrCol.c_str());
     
     //put the moves in the array
     //computers'
     board[compIntRow-1][compIntCol-1] = 'O';
     
     //check if computer wins or board is full
     if (winner('O'))
        break;
     if (full_board('-'))
        break;
     //GAME LOOP ENDS
     //----------------------------------------------------------- 
     } while ((!winner('X')) || (!winner('O')) || (!full_board('-')));
}

//check if user wants to play again
bool check_again(char yn)
{
     char checker = toupper(yn);
     if (checker == 'Y')
        return true;
     if (checker == 'N')
        return false;
}
int main()
{
    //welcome
    cout << "\t\tWELCOME TO TIC TAC TOE!\n\n";
    char again = 'Y';
    do
    {
    play();
    //display end board
    for (int i = 0; i < ROWS; ++i)
    {
         cout << "\t\t\t";
         for (int j = 0; j < COLS; ++j)
         cout << " " << board[i][j];
    cout << endl;
    }
    //announce winner or full board
    if (winner('X'))
    cout << "\nYOU'RE THE WINNER!\n\n";
    if (winner('O'))
    cout << "\nTHE COMPUTER WINS!\n\n";
    if (full_board('-'))
    cout << "\nNO ONE WINS!\n\n";
    
    //play again?
    cout << "Play again? (y/n): ";
    cin >> again;
    if ((check_again(again)) == false)
       {
       cout << "\nOK, goodbye\n\n";
       break;
       }
    if ((check_again(again)) == true)
    {
       moves.clear();
       for (int i = 0; i < ROWS; ++i)
       {
         for (int j = 0; j < COLS; ++j)
             board[i][j] = '-';
       }
    }
    } while (again == 'Y' || again == 'y');
    system("PAUSE");
    return 0;
}

[ToniAz]

Please recopy the code again from your text editor and insert into code tags (<> on the right).

[ThangDo]

It IS a pain to look at code without <code> tag, people !!!

[kevinmur]

Thanks, fixed it up :)

[ThangDo]

To be honest, it is just my own preferences that I use only 1 exit point for any value return function. multiple exit can be difficult to debug in more complex context.

and dont use

system("PAUSE");

I guess.

[Volatile Pulse]

A lot of functions that return values require more than one exit point. Even in more complex functions, you might have more exit points than you have statements in your main.

[ThangDo]

of course, I just try to avoid using multiple exit point as much as possible.

for example, this one is simple and I will avoid using it that way

bool full_board(char full)
{
     bool bResult = true;
     for (int i = 0; i < ROWS; ++i)
     {
         for (int j = 0; j < COLS; ++j)
         {
             if (board[i][j] == full)
             {
                   bResult = false;
             }
         }
     }
     return bResult;
}

you get the idea.

[Volatile Pulse]

Why force the program to use more memory than it needs to when you could simply just return false or true and eliminate the variable?