处理随机数时堆栈溢出/段错误

Question

我正在创建一个小井字棋游戏，并使用此函数随机生成计算机的移动：

//Generates the computer's move randomly
void tictactoe::getComputerMove( char** b )
{
    int rand1,rand2;

    //Generate two random numbers
    rand1 = rand() % 2;//0-2
    rand2 = rand() % 2;//0-2

    //Check if that spot is taken yet.
    if( b[rand1][rand2] == ' ' )//Empty
            b[rand1][rand2] = 'O';

    else //Already filled.
        getComputerMove( b );
}

在人类用户移动后立即循环调用该函数。我认为这是问题的原因是因为我收到的消息正在处理随机数，这是我使用它们的唯一地方。我包含这些文件：

#include "tictactoe.h" //Homemade header file
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string>
#include <iostream>

---

valgrind 生成的错误消息如下所示：

==31280== Stack overflow in thread 1: can't grow stack to 0xbe398ff8
==31280== 
==31280== Process terminating with default action of signal 11 (SIGSEGV)
==31280==  Access not within mapped region at address 0xBE398FF8
==31280==    at 0x41AB4BF: random_r (random_r.c:364)
==31280==  If you believe this happened as a result of a stack
==31280==  overflow in your program's main thread (unlikely but
==31280==  possible), you can try to increase the size of the
==31280==  main thread stack using the --main-stacksize= flag.
==31280==  The main thread stack size used in this run was 8388608.
==31280== Stack overflow in thread 1: can't grow stack to 0xbe398ff4
==31280== 
==31280== Process terminating with default action of signal 11 (SIGSEGV)
==31280==  Access not within mapped region at address 0xBE398FF4
==31280==    at 0x4021430: _vgnU_freeres (vg_preloaded.c:58)
==31280==  If you believe this happened as a result of a stack
==31280==  overflow in your program's main thread (unlikely but
==31280==  possible), you can try to increase the size of the
==31280==  main thread stack using the --main-stacksize= flag.
==31280==  The main thread stack size used in this run was 8388608.
==31280== 
==31280== HEAP SUMMARY:
==31280==     in use at exit: 21 bytes in 4 blocks
==31280==   total heap usage: 4 allocs, 0 frees, 21 bytes allocated
==31280== 
==31280== LEAK SUMMARY:
==31280==    definitely lost: 0 bytes in 0 blocks
==31280==    indirectly lost: 0 bytes in 0 blocks
==31280==      possibly lost: 0 bytes in 0 blocks
==31280==    still reachable: 21 bytes in 4 blocks
==31280==         suppressed: 0 bytes in 0 blocks
==31280== Rerun with --leak-check=full to see details of leaked memory
==31280== 
==31280== For counts of detected and suppressed errors, rerun with: -v
==31280== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 20 from 9)
Segmentation fault

---

创建二维数组的代码：

char** tictactoe::createBoard() { //将其初始化为某个东西 炭**板；

    //Allocate memory for the array
    board = new char* [3];

    for( int i = 0; i < 3; i++ )
    {
        board[i] = new char[3];
    }

    //Now fill each slot with a dummy ' '
    for( int i = 0; i < 3; i++ )
    {
        for( int j = 0; j < 3; j++ )
            board[i][j] = ' ';
    }

    return board;
}

Answer 1

你的 mod 操作 rand() % 2 只会输出 0 或 1，你应该使用 rand() % 3。可能发生的情况是，您只是随机探索整个棋盘的 2x2 子矩阵。

Answer 2

我认为这是问题的原因是因为我收到的消息正在处理随机数

不。当板（准确地说：2x2 上部，因为 %2 只会输出 0 和 1）已满时，它就会崩溃：在这种情况下没有退出条件。相反，您会调用 getComputerMove() 直到堆栈已满：堆栈溢出。