Range based auto loop for multi-dimensional array as a function parameter

Question

Learning about arrays, pointers, and references. Attempting to pass a chessboard 8x8 size array as a function parameter to print the array.

Is it not possible to use a range-based loop, or should I use a basic for-loop? Or am I simply setting the first value incorrectly? Without templates.

The first value [0][0] should be a 1, not multiple 1s.

#include <iostream>
void print(int (&board)[8][8])
{
  for (auto &x : board)
    {
      for (auto &y : board)
        {
          std::cout << board[*x][*y] << '\t';
        }
      std::cout << std::endl;
    }
}

int main (int argc, const char **argv)
{
  // Attempting to initialize all 8x8 to 0
  int board[8][8] = { { 0 } }; 
  // Set position [0][0] to value 1;
  board[0][0] = { 1 };
  // Print chessboard
  print(board);
}

Output

      /*          Output (Incorrect)
       *    0   0   0   0   0   0   0   0   
            0   1   1   1   1   1   1   1   
            0   1   1   1   1   1   1   1   
            0   1   1   1   1   1   1   1   
            0   1   1   1   1   1   1   1   
            0   1   1   1   1   1   1   1   
            0   1   1   1   1   1   1   1   
            0   1   1   1   1   1   1   1   
       *     
       */

Expected

      /*          Output (CORRECT)
       *    1   0   0   0   0   0   0   0   
            0   0   0   0   0   0   0   0
            0   0   0   0   0   0   0   0   
            0   0   0   0   0   0   0   0   
            0   0   0   0   0   0   0   0   
            0   0   0   0   0   0   0   0
            0   0   0   0   0   0   0   0   
            0   0   0   0   0   0   0   0   
       *     
       */

songyuanyao · Accepted Answer · 2019-09-11 09:09:27Z

4

x and y are the element, not the index of the array. You could change the range-based for loop to

for (auto &row : board)
{
  for (auto element : row)
    {
      std::cout << element << '\t';
    }
  std::cout << std::endl;
}

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edited Sep 11, 2019 at 9:09

answered Sep 11, 2019 at 4:12

songyuanyao

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1 Comment

ABC Over a year ago

The correct answer, thanks for the quick response. I have to wait for the time limit to accept this as the correct answer. But this worked, thank you! Will accept. Really appreciate you taking the time out to answer and point this out.

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