C - The variable is being used without being initialized

Question

I'm new to C/C++ programming language. I want to make simple Conway's Game of Life using C programming language.

My code looks like this:

#include "stdafx.h"

// Define some constants
const int DIM = 10;
int board[DIM][DIM];

int checkNeighbours(int x, int y) {
    int left, right, top, bottom = 0;
    int sum;

    // Check neighbour cells
    if (board[x - 1][y]) { left = 1; }
    if (board[x + 1][y]) { right = 1; }
    if (board[x][y - 1]) { top = 1; }
    if (board[x][y + 1]) { bottom = 1; }

    sum = left + right + top + bottom;

    return sum;
}

// Build a board
void buildBoard() {
    int i, j, neighbour_count;

    for (i = 0; i < DIM; i++) {
        for (j = 0; j < DIM; j++){

            neighbour_count = checkNeighbours(i, j);

            // Underpopulation
            if (neighbour_count < 2) { board[i][j] = 0; }
            // Lives if nc is 2 or 3
            // Overpopulation
            if (neighbour_count > 3) {
                board[i][j] = 0;
            }

            // Revive 
            if (neighbour_count == 3) {
                board[i][j] = 1;
            }
        }
    }

    // Predefined board cells
    board[1][2] = 1;
    board[1][3] = 1;
    board[2][2] = 1;
}

void drawBoard() {
    int i, j;

    for (i = 0; i < DIM; i++) {
        for (j = 0; j < DIM; j++) {
            char figure= (board[i][j]) ? 'A' : '_';
            printf("%c", figure);
        }
        printf("\n");
    }
}

int main()
{
    buildBoard();
    drawBoard();

    getchar();
    return 0;
}

Errors I'm getting:

Run-Time Check Failure #3 - The variable 'left' is being used without being initialized.

Run-Time Check Failure #3 - The variable 'right' is being used without being initialized.

Run-Time Check Failure #3 - The variable 'top' is being used without being initialized.

How can I fix this, since I've already initialized those variables.

Answer 1

int left, right, top, bottom = 0; 

is initializing only the last variable. Better:

int left = 0 , right = 0, top = 0, bottom = 0;

or

int left, right, top, bottom;
left = right = top = bottom = 0;

Same flavour:

char* a, b, c, d; 

declares only a as char* pointer, rest of b, c and d are char.