处理随机数时堆栈溢出/ Seg错误

时间:2012-02-18 01:00:11

标签: segmentation-fault stack-overflow valgrind

我正在创建一个小小的tic tac toe游戏,我使用此功能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在循环中调用该函数。我认为这是问题的原因是因为我得到的消息是处理randoms,这是我使用它们的唯一地方。我有这些文件:

#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() {         //将其初始化为某种东西         char ** board;

    //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;
}

2 个答案:

答案 0 :(得分:2)

你的mod操作rand() % 2只输出0或1,你应该使用rand() % 3。可能发生的是你只是随机探索整个电路板的2x2子矩阵。

答案 1 :(得分:1)

  

我认为这是问题的原因是因为我得到的信息是处理randoms

不。它只是在电路板崩溃时(确切地说:2x2上部,因为%2将只输出0和1)已满:在这种情况下没有退出条件。而是在堆栈满了之前调用getComputerMove():堆栈溢出。