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My code is not able to compile clang is stating error in won function.

My code is as follows:

/**
 * fifteen.c
 *
 * Computer Science 50
 * Problem Set 3
 *
 * 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 * Note that usleep is obsolete, but it offers more granularity than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;

// prototypes
void clear(void);
void greet(void);
void init(void);
void draw(void);
bool move(int tile);
bool won(void);

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)
{
    // define a counter and populate the array
    int c = 1;
    for (int i = 0; i < d; i++)
    {
        for (int j = 0; j < d; j++)
        {
        // fill the tiles in descending order
        board[i][j] = d * d - c;
        c++;
        }
    }
    //make the last tile blank
    board[d-1][d-1] = 99;
    // if there are an odd number of tiles, switch 1 and 2
    if ((d * d)%2 == 0)
    {
        board[d-1][d-2] = 2;
        board[d-1][d-3] = 1;
    }
}

/**
 * Prints the board in its current state.
 */
void draw(void)
{
    for (int i = 0; i < d; i++)
    {
        for (int j = 0; j < d; j++) 
            if (board[i][j] == 99)
            // print the blank tile
                printf(" _ ");
            else
            // the tiles in descending order
                printf("%2d ", board[i][j]);
        }
        printf("\n");
    }

/**
 * If tile borders empty space, moves tile and returns true, else
 * returns false. 
 */
bool move(int tile)
{
     // establish algorithm for checking bordering tiles
    for (int i = 0; i < d; i++)
    {
        for (int j = 0; j < d; j++)
        {
            if (board[i][j] == tile)
            {
                //check if the blank is to the right
                if (j+1 <= d-1 && board[i][j+1] == 99)
                {
                    board[i][j+1] = tile;
                    board[i][j] = 99;
                    return true;
                }
                // check if the blank is to the left
                else if (j-1 >= 0 && board[i][j-1] == 99)
                {
                    board[i][j-1] = tile;
                    board[i][j] = 99;
                    return true;
                }
                // check if the blank is above
                else if (i-1 >= 0 && board[i-1][j] == 99)
                {
                    board[i-1][j] = tile;
                    board[i][j] = 99;
                    return true;
                }
                // check if the blank is below
                else if (i+1 <= d-1 && board[i+1][j] == 99)
                {
                    board[i+1][j] = tile;
                    board[i][j] = 99;
                    return true;
                }

            }
        }
    return false;
    }

/**
 * Returns true if game is won (i.e., board is in winning configuration), 
 * else false.
 */
bool won(void)
{
    int n = 1;

    for (int i = 0; i < d; i++)
    {
        for (int j = 0; j < d; j++)
        {
            if (board[i][j] == n)
            {
                n++;
                if (n == d*d && board[d-1][d-1] == 0) // Need to make sure the last tile is blank.
                {
                    return true;
                }
            }
        } 
    }
    return false;
}

I am not able to figure out the problem as everything seems correct to me.The error I am getting is as follows:

fifteen.c:253:1: error: function definition is not allowed here

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I would look carefully at the function that precedes it. If I had to guess, I'd say that the previous function isn't closed, probably because of a mismatch of curly braces.

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  • Thanks for your quick answer. Now I have added my complete codde so that it can help you with finding a solution to my problem. Thanks in advance – Quasar Jul 3 '16 at 21:55
  • Oh no! You need to find this one! ;-) Especially since it's exactly what I said it would be. This one is just too simple to fix! You need to work through it on your own so that you understand the cause and effect for the future. – Cliff B Jul 3 '16 at 22:04
  • Actually I tried adding a closing curly bracket to after move but after that I got another error which states : control may reach end of non-void function [-Werror,-Wreturn-type]. – Quasar Jul 4 '16 at 12:15
  • 1
    So you fixed one problem and discovered another. Welcome to the wonderful world of software debugging! ;-) – Cliff B Jul 4 '16 at 12:21
  • hehe thanks for replying. How should I move further? I am not able to find problems with GDB. – Quasar Jul 4 '16 at 12:26
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Problems I see: inside your loops, you set i < d and j < d, then is impossible n = d*d. Also, if you check board[d-1][d-1] == 0, you checking just the matrix's diagonal. You must consider others, e.g. board[i][j-1] or board[i-1][j]. I am still thinking about my answer... :-|

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