C语言 遇到可识别的分段错误

Question

每当我运行代码时，我都会收到一条消息：Segmentation fault: 11

我的问题是为什么会弹出这条消息。在此之前，我已经做了一些研究并尝试修复它，但我仍然弹出相同的消息。请查看我的代码！

为我的代码提供一些上下文：该程序的目标是在计算机和人类玩家之间实现Connect Four游戏。函数将在文件connect4_functions.c中实现。这些函数的前向声明位于文件 connect4_functions.h 中。connect4.c 包含主要的 () 函数。

代码 (connect4_functions.c) 如下：

#include "connect4_functions.h"
int print_welcome(void) // PROBLEM: returnerer alltid 1
{
printf ("*** Welcome to the Connect Four game!!! ***n");
printf ("Would you like to make the first move [y/n]: ");
if (getchar() == 'N' || getchar() == 'n') return 2;
else return 1;
while (getchar()!= 'n');
}
void display_board(int board[][BOARD_SIZE_VERT])
{
int i, j;
for (i = BOARD_SIZE_VERT-1; i >= 0; i--)
{
for (j = 0; j < BOARD_SIZE_HORIZ; j++) printf ("+---");
printf ("+n");
for (j = 0; j < BOARD_SIZE_HORIZ; j++)
{
switch (board[j][i])
{
case 0: printf ("|   "); break;
case 1: printf ("| O "); break;
case 2: printf ("| X "); break;
}
}
printf ("|n");
} // end for
for (j = 0; j < BOARD_SIZE_HORIZ; j++) printf ("+---");
printf ("+n");
for (j = 1; j <= BOARD_SIZE_HORIZ; j++) printf ("  %d ", j);
printf ("n");

} //end function display_board

int random_move(int board[][BOARD_SIZE_VERT], int computer_num)
{
int m = (rand() % BOARD_SIZE_HORIZ) + 1;
if (!is_column_full(board,m))
{
update_board(board,m,computer_num);
return m;
}
else return random_move(board,computer_num);
}
int player_move(int board[][BOARD_SIZE_VERT], int player_num)
{
int m;
printf ("Please enter your move: ");
scanf ("%d", &m);
while (getchar() != 'n');
if ( 0 > m || m > BOARD_SIZE_HORIZ)
{
printf ("Not a valid move. Enter a column number!n");
return player_move(board, player_num);
}
if (is_column_full(board, m))
{
printf ("This column is full. Try again!n");
return player_move(board, player_num);
}
update_board(board,m,player_num);
return m;
}

bool check_win_or_tie(int board[][BOARD_SIZE_VERT], int last_move)
{
int m, count = 0;
if (check_winner(board, last_move))
{
printf("Player %c won!n", ( check_winner(board,last_move) == 1 ? '1' : '2' ) );
return true;
}
for (m = 0; m < BOARD_SIZE_HORIZ; m++) if ( is_column_full(board, m) ) count++;
if (count == BOARD_SIZE_HORIZ)
{
printf ("Tie game!n");
return true;
}
else return false;
}
bool is_column_full(int board[][BOARD_SIZE_VERT], int m)
{
return (board[m-1][BOARD_SIZE_VERT-1]);
}
void update_board(int board[][BOARD_SIZE_VERT], int m, int player_num)
{
int i;
for ( i = 0; i < BOARD_SIZE_VERT ; i++)
{
if (!board[m-1][i])
{
board[m-1][i] = player_num;
return;
}
}
}
int check_winner(int board[][BOARD_SIZE_VERT], int last_move)
{
int i, row, count;
// Find row
for (row = 0; row < BOARD_SIZE_VERT; row++)
{
if (board[last_move-1][row]) count++;
}
row = count;
printf ("row = %dn", row);
// Vertical
for (i = 0; i < BOARD_SIZE_VERT; i++)
{
if (board[last_move-1][i] == board[last_move-1][row]) count++;
else count = 0;
if (count == 4) return board[last_move-1][row];
else return 0;
}

count = 0; // reset
// Horizontal
for (i = 0; i < BOARD_SIZE_HORIZ; i++)
{
if (board[i][row] == board[last_move-1][row]) count++;
else count = 0;
if (count == 4) return board[last_move-1][row];
else return 0;
}

count = 0; // reset
return 0;
}

connect4_functions.h(无法更改)的代码如下：

#ifndef CONNECT4_FUNCTIONS
#define CONNECT4_FUNCTIONS

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <stdbool.h>

#define BOARD_SIZE_HORIZ 7
#define BOARD_SIZE_VERT 6

int print_welcome(void);

void display_board(int board[][BOARD_SIZE_VERT]);

int random_move(int board[][BOARD_SIZE_VERT], int computer_num);

int player_move(int board[][BOARD_SIZE_VERT], int player_num);

bool check_win_or_tie(int board[][BOARD_SIZE_VERT], int last_move);

bool is_column_full(int board[][BOARD_SIZE_VERT], int m);

void update_board(int board[][BOARD_SIZE_VERT], int m, int player_num);

int check_winner(int board[][BOARD_SIZE_VERT], int last_move);

int best_move(int board[][BOARD_SIZE_VERT], int computer_num);

#endif

connect4.c的代码(也无法更改)如下：

#include "connect4_functions.h"
int main()
{
int board[BOARD_SIZE_HORIZ][BOARD_SIZE_VERT] = { {0} };
int player_num, computer_num;
int last_move;

/* Ask Alice if she wants to go first */
player_num = print_welcome();
if (player_num == 1) computer_num = 2;
else computer_num = 1;
/* If Alice wants to go first, let her make a move */
if (player_num == 1)
{
display_board(board);
last_move = player_move(board,player_num);
display_board(board);
}

/* The main loop */
while (1)
{
/* Make a computer move, then display the board */
last_move = random_move(board,computer_num);
printf("Computer moved in column: %dn", last_move);
display_board(board);
/* Check whether the computer has won */
if (check_win_or_tie(board,last_move)) return 0;

/* Let Alice make a move, then display the board */
last_move = player_move(board,player_num);
display_board(board);
/* Check whether Alice has won */
if (check_win_or_tie(board,last_move)) return 0;

} /* end of while (1) */
} /* end of main() */

另外，如果您想查看原始pdf，请在下面链接：

链接到 pdf

输出为：

*** Welcome to the Connect Four game!!! ***
Would you like to make the first move [y/n]: y
+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+
1   2   3   4   5   6   7 
Please enter your move: 4
+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+
|   |   |   | O |   |   |   |
+---+---+---+---+---+---+---+
1   2   3   4   5   6   7 
Computer moved in column: 1
+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+
| X |   |   | O |   |   |   |
+---+---+---+---+---+---+---+
1   2   3   4   5   6   7 
row = -355898527
Segmentation fault: 11

(如果您对上下文或目的有任何疑问，请随时询问！

Answer 1

没有实际运行代码，我相信问题可能是计数没有在check_winner中初始化：

int check_winner(int board[][BOARD_SIZE_VERT], int last_move)
{
int i, row, count;
// Find row
for (row = 0; row < BOARD_SIZE_VERT; row++)
{
if (board[last_move-1][row]) count++;
}
row = count;
// WHAT IF IT EXITS THE for () WITHOUT board[last_move-1][row] being non-zero?
// HINT: count can be anything!
printf ("row = %dn", row);

然后，您将row用作对阵列的访问，然后轰隆隆！您访问了超出权限的内存。

Answer 2

在check_winner函数中，您不初始化变量计数。我得到一个单位化变量运行时错误，但如果我稍后继续前进几行，然后设置：

row = count;

在我的例子中，将行设置为 -858993459;

在你写的同一个函数中，有几行：

if (board[last_move - 1][i] == board[last_move - 1][row]) count++; 
// You use "row", an initialised variable as the index
// for the second subscript operator of board.

这就是我得到的地方：

Access violation reading location 0x0000005663E82BB4. occurred

我认为应该对这个单位化变量发出警告。老实说，我不知道这是否是它的全部问题，但它看起来是一款相当不错的游戏。

Answer 3

首先，为了能够解决您的问题，您应该确保在崩溃之前可能打印的所有内容都已打印出来。在此目标中，您应该在每个打印指令之后添加一条fflush(stdout);指令

其次，如果这不能明确编程崩溃的位置，则应在发生崩溃的代码段中添加补充跟踪指令。

然后，当您确定哪个指令导致 de 崩溃时，您应该打印它的变量以检查它们的值是否是您所期望的。

或者，您可以使用assert指令来确保变量值都在预期范围内。