error: unused parameter 'tile' - c

Question

I tried everything and my Game of Fifteen is one error away from being compiled.
The only issue is that somehow I get the "unused parameter error", telling me that my code does not make use of the tile parameter...which it should!
Here's the error:
fifteeen.c:312:15: error: unused parameter 'tile' [-Werror,-Wunused-parameter]
void swaptile(tile)
1 error generated.
And here's the code
/**
* fifteen.c
*
* Implements Game of Fifteen (generalized to d x d).
*
* Usage: fifteen d
*
* whereby the board's dimensions are to be d x d,
* where d must be in [DIM_MIN,DIM_MAX]
*
* Note that usleep is obsolete, but it offers more granularity than
* sleep and is simpler to use than nanosleep; `man usleep` for more.
*/
#define _XOPEN_SOURCE 500
#include <cs50.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
// constants
#define DIM_MIN 3
#define DIM_MAX 9
// board
int board[DIM_MAX][DIM_MAX];
// dimensions
int d;
int tile_row;
int tile_column;
int blank_row;
int blank_column;
// prototypes
void clear(void);
void greet(void);
void init(void);
void draw(void);
bool move(int tile);
bool won(void);
void search(int tile);
bool legalmove(void);
void swaptile(int tile);
int main(int argc, string argv[])
{
// ensure proper usage
if (argc != 2)
{
printf("Usage: fifteen d\n");
return 1;
}
// ensure valid dimensions
d = atoi(argv[1]);
if (d < DIM_MIN || d > DIM_MAX)
{
printf("Board must be between %i x %i and %i x %i, inclusive.\n",
DIM_MIN, DIM_MIN, DIM_MAX, DIM_MAX);
return 2;
}
// open log
FILE* file = fopen("log.txt", "w");
if (file == NULL)
{
return 3;
}
// greet user with instructions
greet();
// initialize the board
init();
// accept moves until game is won
while (true)
{
// clear the screen
clear();
// draw the current state of the board
draw();
// log the current state of the board (for testing)
for (int i = 0; i < d; i++)
{
for (int j = 0; j < d; j++)
{
fprintf(file, "%i", board[i][j]);
if (j < d - 1)
{
fprintf(file, "|");
}
}
fprintf(file, "\n");
}
fflush(file);
// check for win
if (won())
{
printf("ftw!\n");
break;
}
// prompt for move
printf("Tile to move: ");
int tile = GetInt();
// quit if user inputs 0 (for testing)
if (tile == 0)
{
break;
}
// log move (for testing)
fprintf(file, "%i\n", tile);
fflush(file);
// move if possible, else report illegality
if (!move(tile))
{
printf("\nIllegal move.\n");
usleep(500000);
}
// sleep thread for animation's sake
usleep(500000);
}
// close log
fclose(file);
// success
return 0;
}
/**
* Clears screen using ANSI escape sequences.
*/
void clear(void)
{
printf("\033[2J");
printf("\033[%d;%dH", 0, 0);
}
/**
* Greets player.
*/
void greet(void)
{
clear();
printf("WELCOME TO GAME OF FIFTEEN\n");
usleep(2000000);
}
/**
* Initializes the game's board with tiles numbered 1 through d*d - 1
* (i.e., fills 2D array with values but does not actually print them).
*/
void init(void)
{
/* total tiles to be initialised */
int total_tiles = (d * d) - 1;
/* loop 2D array with outer loop row: fill tiles one by one
left to right (column) then top to bottom (rows)*/
for (int index_row = 0; index_row < d ; index_row++)
{
for (int index_column = 0; index_column < d ; index_column++)
{
board [index_row][index_column] = total_tiles;
total_tiles--;
}
printf("\n");
}
/* if d even, the number of tiles odd, then swap tile 1 and 2 */
if (((d*d) - 1) % 2 != 0)
{
int temp = board[d-1][d-2];
board[d-1][d-2] = board[d-1][d-3];
board[d-1][d-3] = temp;
}
/* mark where your empty tile is */
blank_row = d-1;
blank_column = d-1;
}
/**
* Prints the board in its current state.
*/
void draw(void)
{
/* Print the board, if tile 0 print underscore */
for (int index_row = 0; index_row < d; index_row++)
{
for (int index_column = 0; index_column < d; index_column++)
{
if (board[index_row][index_column] < 10)
{
if (board[index_row][index_column] == 0)
{
printf(" [_] ");
}
else
{
printf(" [%d] ", board[index_row][index_column]);
}
}
else
{
printf("[%d] ", board[index_row][index_column]);
}
}
/* print space before printing next line */
printf("\n");
}
}
/**
* If tile borders empty space, moves tile and returns true, else
* returns false.
*/
bool move(int tile)
{
/* sanity check for tile's existance */
if (tile > (d*d)-1 || tile < 1)
return false;
/* linear search for tile inputted by user */
search(tile);
/* Once we found the tile, we swap if move is legal */
if (legalmove())
{
swaptile(tile);
return true;
}
else
return false;
return false;
}
/**
* Returns true if game is won (i.e., board is in winning configuration),
* else false.
*/
bool won(void)
{
/*set counter and check if last tile empty */
int counter = 1;
/* Check if every tile corresponds to the an arthmetic sequence start = 1, constant = +1 */
for(int index_row = 0; index_row < d; index_row++)
{
for(int index_column = 0; index_column < d; index_column++)
{
if (board[index_row][index_column] == counter)
counter++;
}
}
if (counter == d*d && board[d-1][d-1] == 0)
return true;
else
return false;
}
/* linear search for tile */
void search(int tile)
{
for (int index_row = 0; index_row < d; index_row++)
{
for(int index_column = 0; index_column < d; index_column++)
{
/* if tile found */
if (board[index_row][index_column] == tile)
{
tile_row = index_row;
tile_column = index_column;
}
}
}
}
/* check if blank space bordering with the tile found*/
bool legalmove(void)
{
/* check if space on top row */
if (tile_row > 0 && board[tile_row - 1][tile_column] == 0)
return true;
/* bottom */
if (tile_row < d - 1 && board[tile_row + 1][tile_column] == 0)
return true;
/* left */
if (tile_column > 0 && board[tile_row][tile_column - 1] == 0)
return true;
/* right */
if (tile_column < d - 1 && board[tile_row][tile_column + 1] == 0)
return true;
else
return false;
}
/* swap and update tile position */
void swaptile(tile)
{
int temp = board[tile_row][tile_column];
board[tile_row][tile_column] = board[blank_row][blank_column];
board[blank_row][blank_column] = temp;
blank_row = tile_row;
blank_column = tile_column;
}

Answer 1

You get the warning because in swaptile the tile parameter is actually not used (check yourself) and because you compiled with -Wunused-parameter:
/* swap and update tile position */
void swaptile(tile)
{
/* tile parameter is not used in this function */
int temp = board[tile_row][tile_column];
board[tile_row][tile_column] = board[blank_row][blank_column];
board[blank_row][blank_column] = temp;
blank_row = tile_row;
blank_column = tile_column;
}
... and it is actually an error because you compiled with -Werror, which considers all warnings as errors.
Sou you just should have
void swaptile()
instead of
void swaptile(tile)
BTW: void swaptile(tile) should be void swaptile(int tile), (implicit int types in function declarations are somewhat depcrecated and some compiler don't even accept it anymore).