Smiles in output C++ - c++

Question

I'm writing Tic Tac Toe console game at the moment and I have one very funny problem. The program is working great, but the problem is in matrix of Tic Tac Toe. The last element (last row, last column) is a smile and it's sometimes changing. It is sometimes laughing smile, or it is a heart. What's wrong?
The whole code:
#include <iostream>
#include <string>
#include <string.h>
#include <vector>
#include <stdlib.h>
using namespace std;
char matrix[3][3];
int orow, ocolumn, xrow, xcolumn;
int drawcounter = 0;
void paint() {
for (int i = 1; i < 4; i++) {
for (int j = 1; j < 4; j++)
matrix[i][j] = '_';
}
}
void board() {
for (int i = 1; i < 4; i++)
for (int j = 1; j < 4; j++) {
if (i != 1 && j == 1)
cout << endl;
cout << matrix[i][j] << " ";
}
cout << endl;
//cout << matrix[3][3] << endl;
}
void action() {
while (0 == 0) {
puts("Time for player X. Enter index");
cin >> xcolumn >> xrow;
matrix[xcolumn][xrow] = 'X';
drawcounter += 1;
if (drawcounter == 9) {
puts("It's a draw.");
break;
}
board();
cout << endl;
if ((matrix[1][1] == 'X' && matrix[2][2] == 'X' && matrix[3][3] == 'X') || (matrix[1][3] == 'X' && matrix[2][2] == 'X' && matrix[3][1] == 'X')) {
puts("X Wins! Congrats X!");
break;
}
if ((matrix[1][1] == 'X' && matrix[1][2] == 'X' && matrix[1][3] == 'X') || (matrix[2][1] == 'X' && matrix[2][2] == 'X' && matrix[2][3] == 'X') || (matrix[3][1] == 'X' && matrix[3][2] == 'X' && matrix[3][3] == 'X')) {
puts("X Wins! Congrats X!");
break;
}
if ((matrix[1][1] == 'X' && matrix[2][1] == 'X' && matrix[3][1] == 'X') || (matrix[1][2] == 'X' && matrix[2][2] == 'X' && matrix[3][2] == 'X') || (matrix[1][3] == 'X' && matrix[2][3] == 'X' && matrix[3][3] == 'X')) {
puts("X Wins! Congrats X!");
break;
}
puts("Time for player O. Enter index");
cin >> ocolumn >> orow;
matrix[ocolumn][orow] = 'O';
drawcounter += 1;
board();
cout << endl;
if ((matrix[1][1] == 'O' && matrix[2][2] == 'O' && matrix[3][3] == 'O') || (matrix[1][3] == 'O' && matrix[2][2] == 'O' && matrix[3][1] == 'O')) {
puts("O Wins! Congrats O!");
break;
}
if ((matrix[1][1] == 'O' && matrix[1][2] == 'O' && matrix[1][3] == 'O') || (matrix[2][1] == 'O' && matrix[2][2] == 'O' && matrix[2][3] == 'O') || (matrix[3][1] == 'O' && matrix[3][2] == 'O' && matrix[3][3] == 'O')) {
puts("O Wins! Congrats O!");
break;
}
if ((matrix[1][1] == 'O' && matrix[2][1] == 'O' && matrix[3][1] == 'O') || (matrix[1][2] == 'O' && matrix[2][2] == 'O' && matrix[3][2] == 'O') || (matrix[1][3] == 'O' && matrix[2][3] == 'O' && matrix[3][3] == 'O')) {
puts("O Wins! Congrats O!");
break;
}
}
}
int main() {
paint();
board();
action();
system("pause");
return 0;
}
Output pictures:

Answer 1

Array indexing in C/C++ start from 0, not from 1 - so you have to rewrite your code:
void paint() {
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 3; j++)
matrix[i][j] = '_';
}
}
void board() {
for (int i = 0; i < 3; i++)
for (int j = 0; j < 3; j++) {
if (i != 0 && j == 0)
cout << endl;
cout << matrix[i][j] << " ";
}
cout << endl;
//cout << matrix[3][3] << endl;
}
What's actually is going on here, in detail: when you define your array, you should remember that indexing starts from 0, so for example when you declare an array of 3 elements, matrix[3], it's not going like matrix[1], matrix[2], and matrix[3], but rather matrix[0], matrix[1], and matrix[2].
So in this case you're getting out of an array bounds - and it's "here be dragons" territory outside of a memory region assigned to an array. So basically you're working with raw memory here, which in your situation contains a character code for a smiley face (and that's why it's different every time - because memory content isn't determined in this region - e.g., you can even try to get a value of matrix[123], though its size is only 3 elements - and you get an undefined random value as a result).
And you should remember that C/C++ arrays behavior is very similar to pointers in this regard - you might even say that it's the same thing.

Answer 2

In C++, arrays are indexed from 0. So in your loop in paint()
for(int i = 1; i < 4; ++i) // out of bounds when `i = 3`
you have an out of bound access, as matrix is declared as
char matrix[3][3];
You have to replace all such loops with loops from 0 to 3. Also, your if conditions are probably wrong
if ((matrix[1][6] == 'X' && matrix[2][7] .... // 6 and 7 ?!?!
as the row/column indexes cannot be greater than 2

Answer 3

char matrix[3][3];
[...]
matrix[3][3] == 'O'
This won't work. Array indices start at 0. So you've declared an array of size 3 and then access its 4th element. This is undefined behaviour. Which means anything can happen, including crashes or printing seemingly random characters.
Note that using raw arrays like this may raise an eyebrow or two. If you ever want the ability to determine matrix size dynamically (e.g. via user input), you will want to use std::vector anyway. And if the size is really conceptually meant to be known at compile time (which admittedly may be the case for a game like this), consider using std::array, or at least get informed on its syntax and benefits.

Answer 4

Maybe you are trying to store 1 in a char array as
#include<iostream>
using namespace std;
int main()
{
char n=1;
cout << n;
return 0;
}
The output will be a smiley