Long Code with a segmentation fault

[shortikid12]

Sorry for the long code, but I am completely stumped with trying to get a simple Tic Tac toe game going. Once I get into the MakeAMove function, it breaks.

Also, if there are any beginner tips to improving this code, I would love to hear them.

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

using namespace std;

void Intro();
void TicTacDefault(vector<int>& rboard);
void TicTacDisplay(vector<int>& rboard);

char playerXorO();
char computerXorO(char PLAYER);

char MakeaMove(char PLAYER, char COMP);
void Pmove(char);
void Cmove(char);
int CompCalc(char);

bool IsLegal(int, vector<int>& rboard);
void UpdateBoard(char, int, vector<int>& rboard);

bool WhoWins(char a);
bool WinningMoves(char a, vector<int>& rboard);

vector<int> board;
vector<int>& rboard = board;

int main()
{
    Intro();

    vector<int> board;
    vector<int>& rboard = board;

    TicTacDefault(rboard);
    TicTacDisplay(rboard);

    const char PLAYER=playerXorO();
    const char COMP=computerXorO(PLAYER);

    cout << PLAYER << endl;
    cout << COMP << endl;

    if (MakeaMove(PLAYER, COMP)==PLAYER)
        cout << "Player Wins!";
    else
        cout << "Computer Wins";

    return 0;
}

void Intro()
{
    cout << "\nTic Tac Toe!\n\n";
    cout << "\nYou and a computer will go at it to see who the Tic-Tac-Toe champion is!\n";
    cout << "See if you can beat him!\n";
    cout << "Simply input the number that corresponds to each position.\n";
}

void TicTacDefault (vector<int>& rboard)
{
    rboard.push_back(1);
    rboard.push_back(2);
    rboard.push_back(3);
    rboard.push_back(4);
    rboard.push_back(5);
    rboard.push_back(6);
    rboard.push_back(7);
    rboard.push_back(8);
    rboard.push_back(9);
}

void TicTacDisplay (vector<int>& rboard)
{
    cout << "\n\t " << rboard[0] << " | " << rboard[1] << " | " << rboard[2] << '\n';
    cout << "\t---|---|---\n";
    cout << "\t " << rboard[3] << " | " << rboard[4] << " | " << rboard[5] << '\n';
    cout << "\t---|---|---\n";
    cout << "\t " << rboard[6] << " | " << rboard[7] << " | " << rboard[8] << '\n';
    return;
}


//WHO IS WHO?

char playerXorO()
{
    char playerChoice;

    cout << "\nBut first, take your pick,";
    TypeAgain:
    cout << " X or O? X goes first.\n";

    cin >> playerChoice;

    toupper(playerChoice);
    if (playerChoice=='X')
        {
            cout << "\nYou'll go first\n";
            return 'X';
        }
    else if (playerChoice=='O')
            {
                 cout << "\nLooks like i'll be going first\n";
                 return 'O';
            }
            else ({ //ask for player input again if answer is nonexistent
                  cout << "That's not a choice\n";
                  goto TypeAgain;
                  });
}

inline char computerXorO (char PLAYER)
{
    if (PLAYER=='X')
        {
            const char COMP='O';
            return COMP;
        }
    else
        {
            const char COMP='X';
            return COMP;
        }
}

//Dictate order, update board with moves, check if they are legal

char MakeaMove(char PLAYER, char COMP) //dictate order
{
    if(PLAYER=='X' && COMP=='O') //player goes first
    {
        do
        {
            Pmove(PLAYER);
            if (WhoWins(PLAYER)==true)
                return PLAYER;
            Cmove(COMP);
        } while(WhoWins(COMP)!=true);

        return COMP;
    }
    else if(PLAYER=='O' && PLAYER=='X') //computer goes first
    {
        do
        {
            Cmove(COMP);
            if (WhoWins(COMP)==true)
                return COMP;
            Pmove(PLAYER);
        } while (WhoWins(PLAYER)!=true);

        return PLAYER;
    }
}

void Pmove(char PLAYER) //the player enters a move, checks if legal, updates board
{

    int i;
    cout << "\nYour move\n";
    TicTacDisplay(rboard);
    cout << endl;

    do
    {
        cin >> i;
        IsLegal(i,rboard);
    } while (IsLegal(i, rboard)!=1);
    UpdateBoard(PLAYER, i, rboard);
}

void Cmove(char COMP)//computer calculates a move, checks if legal, updates board
{
    int i;
    cout << "\nMy move\n";

    do
    {
        i=CompCalc(COMP);
        IsLegal(i,rboard);
    } while (IsLegal(i,rboard)!=true);
    UpdateBoard(COMP, i, rboard);

}

bool IsLegal(int i, vector<int>&rboard)
{
    cout << "isLegal";
    if (rboard[i]!='X' || rboard[i]!='O' || i<9)
        {
            return true;
        }
    cout << "\nThat move is illegal! Try again.\n";
    return false;
}

void UpdateBoard (char a, int i, vector<int>& rboard)
{
    rboard[i]=a;
    TicTacDisplay(rboard);
}

int CompCalc(char a) //right now just stupid.
{
    cout << "peepee";
    for (vector<int>::const_iterator iter=rboard.begin(); iter<rboard.end(); ++iter)
        {
        if (*iter=='X' || *iter=='O' || *iter<9)
            {
                break;
                return *iter;
            }
        }
}

//WINNING CHECKS

bool WhoWins(char a)
{
    if (WinningMoves(a, rboard)==true)
        return true;
    else
        return false;
}

bool WinningMoves(char a, vector<int>& rboard)//a is PLAYER or COMP
{
    if (rboard[0]==a && rboard[1]==a && rboard[2]==a)
        return true;
    else if (rboard[0]==a && rboard[3]==a && rboard[6]==a)
        return true;
    else if (rboard[0]==a && rboard[4]==a && rboard[8]==a)
        return true;
    else if (rboard[1]==a && rboard[4]==a && rboard[7]==a)
        return true;
    else if (rboard[2]==a && rboard[5]==a && rboard[8]==a)
        return true;
    else if (rboard[2]==a && rboard[4]==a && rboard[6]==a)
        return true;
    else if (rboard[3]==a && rboard[4]==a && rboard[5]==a)
        return true;
    else if (rboard[6]==a && rboard[7]==a && rboard[8]==a)
        return true;
    else
        return false;
}

[theturk1234]

Ok,
First, make sure you are testing for the capital letter O rather than the number zero in char MakeaMove(char PLAYER, char COMP)
My guess is, you are testing for the wrong values. It is hard to tell which you used with this font. Even if you are testing the wrong value, I think there is still a problem. Let me know if this fixes the problem.
Also, in int CompCalc(char a), you are not returning a value from the function even though it says it returns an int. Pay attention to the compiler's warnings!
Good luck!

[Chervil]

Something looks odd around lines 26/27 and 33/34.

You have both a local variable and a global variable with the same name. Only one of them is initialised. At some point function TicTacDisplay() is called and rboard has a size of zero. Attempting to access elements which don't exist is the cause of the fault.

Usually the advice is to avoid global variables. Acting on that, you'd delete lines 26 and 27 and then see which parts of the code need fixing.

If you are certain that there will only ever be one board and the entire program will be using it, a case might be made for keeping lines 26/27 and instead deleting lines 33/34. I'm uncomfortable suggesting that, It's not good to get into a habit of using global variables.