Value of 2D Array not being change by switch statement - c++

Question

I am trying to code a game of Tic-Tac-Toe, but for some reason my switch function doesn't appear to be running. What am I doing wrong?
#include <iostream>
using namespace std;
int n = 0;
int Player[2] {1, 2};
int moveChosen=0;
int n1 = 0, n2 = 0;
void Display(int grid[][3], int row, int column)
{
cout<<"Coordinates: \n";
cout<<"1"<<" | "<<"2"<<" | "<<"3"<<"\n";
cout<<"--|---|--\n";
cout<<"4"<<" | "<<"5"<<" | "<<"6"<<"\n";
cout<<"--|---|--\n";
cout<<"7"<<" | "<<"8"<<" | "<<"9"<<"\n";
cout<<"Current Moves: \n";
cout<<grid[0][0]<<" | "<<grid[0][1]<<" | "<<grid[0][2]<<"\n";
cout<<"--|---|--\n";
cout<<grid[1][0]<<" | "<<grid[1][1]<<" | "<<grid[1][2]<<"\n";
cout<<"--|---|--\n";
cout<<grid[2][0]<<" | "<<grid[2][1]<<" | "<<grid[2][2]<<"\n";
}
int moveChoice(int Choice)
{
cout<<"Player "<<Player[n]<<" please pick where to move. ";
cin>>Choice;
if (Choice < 1 || Choice > 9)
{
while (Choice < 1 || Choice > 9)
{
cout << "Invalid choice, please enter a new number: ";
cin >> Choice;
}
}
return Choice;
}
void CheckMoveValid(int grid[][3], int Choice)
{
switch (Choice)
{
case 1:
if(grid[0][0] != 0)
{
cout<<"Invalid move, space already filled. ";
}
else
{
moveChosen = Player[n];
n1 = 0;
n2 = 0;
break;
}
break;
case 2:
if(grid[0][1] != 0)
{
cout<<"Invalid move, space already filled. ";
}
else
{
moveChosen = Player[n];
n1 = 0;
n2 = 1;
break;
}
}
}
int main()
{
int grid[3][3]={{0, 0, 0}, {0, 0, 0}, {0, 0, 0}};
int Choice, CheckWin = 0;
while (CheckWin < 1)
{
Display(grid, 3, 3);
moveChoice(Choice);
CheckMoveValid(grid, Choice);
if (n=0)
{
n = 1;
}
else
{
n = 0;
}
grid[n1][n2] = Player[n];
}
return 0;
}
If I put cout << "0" << endl; between line 65 and 66, nothing happens even when I enter 1, and whatever I tried I could not get "Invalid move, space already filled. " to trigger.

Answer 1

In main(), the call to moveChoice() prompts the user for input, but then discards that input. The Choice variable in main() is never assigned a value, so the call to CheckMoveValid() exhibits undefined behavior.
Get rid of the Choice parameter in moveChoice(), it is not needed. Have main() assign the return value of moveChoice() to the Choice variable, eg:
int moveChoice()
{
int Choice;
...
cin >> Choice;
...
return Choice;
}
...
int main()
{
...
int Choice;
...
Choice = moveChoice(); // <-- HERE!!!
CheckMoveValid(grid, Choice);
...
}