c++ - 线程堆栈错误

Question

我的代码有问题，但无法解决。我有三个线程，线程 1 接受两个十六进制数字的输入，线程 2 和 3 将前两位数字与后两位数字交换并打印结果。

错误消息:

Run-Time Check Failure #2 - Stack around the variable 'str' was corrupted.

DWORD WINAPI changevalue( LPVOID lpParam )
{
    WaitForSingleObject(inThread,INFINITE); //Input thread
    printf("thread 1 and 2 running \n");

    int num = 0;
    num = (int)lpParam;
    int i = 0;

    char str[10] ={0};
    char a,b;
    _itoa(num,str,16);

    while (str[i] != NULL)
    {
        i++; //Get location of last char..
    }
    //Exchange first two digits with last two.
    a = str[0];
    b = str[1];

    str[0] = str[i-2];
    str[1] = str[i-1];
    str[i-2] = a;
    str[i-1] = b;
    printf("num=%s\n",str);
    //long numl=strtol(str,&stop,16);
    //printf("num = %x\n", numl);
    //We can also take input to a string then manuplate it, and 
    //then print it in form of a string only.
    //But int is used since it is mentioned in the statement.
    printf("thread 1 and 2 exit......\n ");
    return TRUE;
}

Answer 1

如果lParam为0，调用_itoa(num, str, 16)将得到单字符字符串"0”。

在这种情况下，i 将是 1，并且 str[i - 2] = a 将写在之前 字符串，从而破坏堆栈。

更一般地说，lParam 的值范围从 0 到 15(含)都会触发问题。