c - 我在 cs50 15.c 项目中的 C 语言中有一个 undefined reference

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我正在 cs50 类(class)第三周的 15.c 项目上工作，该项目是 C 编程语言。我对 bool 'won' 有一个 undefined reference ，有人可以解释一下为什么会发生这种情况以及如何修复它吗？谢谢，这是我的代码。

/**
 * 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 * Note that usleep is obsolete, but it offers more granularity than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)
{ 

int tile = d * d - 1;

    // row
    for (int row = 0; row < d; row++)
    {
        // col
        for (int col = 0; col < d; col++) 
        {
            /*if (tile == 0) {
                tile = atoi(placeholder);
            }*/
                board[row][col] = tile;
                tile --;
        }
    }

     // swap 1 and 2 if # of tiles is odd
     if (d*d %2 > 0) {
        board[d-1][d-3] = 1;
        board[d-1][d-2] = 2;
     }
}

/**
 * Prints the board in its current state.
 */
void draw(void)
{
    for (int row = 0; row < d; row++) {
        for (int col = 0; col < d; col++) {
            // if we're at 0, replace with "_"
            //if ((row == d-1) && (col == d-1)) {
              //  printf(" _ \n");
           // }
            // draw the tile
            //else {
                printf("%2d ", board[row][col]);
        //}
    }
    printf("\n");  
}
}
/**
 * If tile borders empty space, moves tile and returns true, else
 * returns false. 
 */
bool move(int tile)
{
    // TODO
        // search for tile for it's position
        // set blank tile to a variable

        // plus or minus one row
        // plus or minus one col

       /* int tile_row;
        int tile_col; */
        int blank_row;
        int blank_col;

        // find the position of the blank tile and the tile 
        for (int row = 0; row < d; row++) {
            for (int col = 0; col < d; col++) {
               /* if (board[row][col] == tile) {
                    tile_row = board[row];
                    tile_col = board[col];
                } */
                if (board[row][col] == 0) {
                    blank_row = row;
                    blank_col = col;
                }
            }
        }

        if (tile == board[blank_row][blank_col-1]) {
            board[blank_row][blank_col] = tile;
            board[blank_row][blank_col-1] = 0;
            return true;
        }
        else if (tile == board[blank_row][blank_col+1]) {
            board[blank_row][blank_col] = tile;
            board[blank_row][blank_col+1] = 0;
            return true;
        }
        else if (tile == board[blank_row-1][blank_col]) {
            board[blank_row][blank_col] = tile;
            board[blank_row-1][blank_col] = 0;
            return true;
        }
        else if (tile == board[blank_row+1][blank_col]) {
            board[blank_row][blank_col] = tile;
            board[blank_row+1][blank_col] = 0;
            return true;
        }
    return false;
}
/**
 * Returns true if game is won (i.e., board is in winning configuration), 
 * else false.
 */
void save(void)
{
    // log
    const string log = "log.txt";

    // delete existing log, if any, before first save
    static bool saved = false;
    if (!saved)
    {
        unlink(log);
        saved = true;
    }

    // open log
    FILE* p = fopen(log, "a");
    if (p == NULL)
    {
        return;
    }

    // log board
    fprintf(p, "{");
    for (int i = 0; i < d; i++)
    {
        fprintf(p, "{");
        for (int j = 0; j < d; j++)
        {
            fprintf(p, "%i", board[i][j]);
            if (j < d - 1)
            {
                fprintf(p, ",");
            }
        }
        fprintf(p, "}");
        if (i < d - 1)
        {
            fprintf(p, ",");
        }
    }
    fprintf(p, "}\n");

    // close log
    fclose(p);
}

Answer 1

您的代码缺少函数won的实现。要修复它，请添加以下功能:

bool won(void)
{
    /* Your code here */
}