I'm not sure why this program won't compile

Question

Here is my program:

#include<stdio.h>
#define COL 3;

void copy_row(int arr1[][COL], int rows, int arr2[], int r);

void copy_row(int arr1[][COL], int rows, int arr2[], int r){
  int i;
  if(r >= rows || r < 0)
    return;

  for(i = 0; i < COL; i++){
    arr1[r][i] = &arr2[i];
  }
}

int main(void){

  return 0;
}

When I try to compile this with gcc, it says "error: expected ']' before ';' token" on line 4 and line 6.

Also, refer to the for-loop, would "arr1[r][i] = arr2[i];" do the samething as "arr1[r][i] = &arr2[i];"? Which is is (more) correct?

Answer 1

The macro COL is expanded to 3; , so inside your declaration and definition looks like this:

int arr1[][3;]

Remove the semi-colon from your #define line.

Also, refer to the for-loop, would arr1[r][i] = arr2[i]; do the same thing as arr1[r][i] = &arr2[i]; ?

No. The first one is correct. The lvalue arr1[r][i] refers to an integer. The rvalue arr2[i] is also an integer.

If you reference it by taking &arr2[i] then its type becomes int* , and is a pointer to element i , and you try to assign that to an lvalue of type int . If you try to do that, your compiler should warn you.