Question

I am trying to write a function that accepts an array as a parameter. However, the C compiler (lcc) is issuing a warning (i.e. my file still compiles) that “.\tetris.c:179: warning: declaration of `clear_array’ does not match previous declaration at .\tetris.c:172”.

Here is the portion of my code involving the function and a call to that function that’s raising the warning:

void remove_filled_rows ()
{
    int row;
    for (row = 0; row < NROWS; row++) {
        // [snip] 
        if (col == NCOLS) {
            clear_array (cells[row]);    // line 172
        }
    }

}

/* Helper method that clears a row */
void clear_array (lc4uint row_array[]) {    // line 179
    int col;
    for (col = 0; col < NCOLS; col++) {
        row_array[col] = 0;
    }
}

My array is declared as follows:

lc4uint cells[NROWS][NCOLS];

where NROWS and NCOLS are integer constants, and lc4uint is simply a typedef to unsigned int.

Answer 1

The declaration has to come before the access. Either move clear_array to before you call it or add a prototype for the clear_array function prior to the call. You should have gotten an error/warning about this on any decent compiler.

The give away — line 172 wasn’t supposed to be the declaration, line 179 was. But the error said 172 was the declaration.