title: C - The variable is being used without being initialized
body: <p>I'm new to <code>C/C++</code> programming language. I want to make simple <strong><a href="http://en.wikipedia.org/wiki/Conway%27s_Game_of_Life" rel="nofollow">Conway's Game of Life</a></strong> using <code>C programming language</code>. </p>
  
  <p><strong>My code</strong> looks like this:</p>
  
  <pre><code>#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 &lt; DIM; i++) {
          for (j = 0; j &lt; DIM; j++){
  
              neighbour_count = checkNeighbours(i, j);
  
              // Underpopulation
              if (neighbour_count &lt; 2) { board[i][j] = 0; }
              // Lives if nc is 2 or 3
              // Overpopulation
              if (neighbour_count &gt; 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 &lt; DIM; i++) {
          for (j = 0; j &lt; DIM; j++) {
              char figure= (board[i][j]) ? 'A' : '_';
              printf("%c", figure);
          }
          printf("\n");
      }
  }
  
  int main()
  {
      buildBoard();
      drawBoard();
  
      getchar();
      return 0;
  }
  </code></pre>
  
  <p><strong>Errors</strong> I'm getting:</p>
  
  <pre><code>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.
  </code></pre>
  
  <p>How can I fix this, since I've already initialized those variables.</p>