線程堆棧錯誤

Question

我在代碼中遇到問題，無法弄清楚。我有三個線程，線程1以十六進制輸入兩個數字，線程2和3將這兩個數字與最後兩個數字交換並打印結果。

錯誤消息：

運行時檢查失敗＃2 - 圍繞堆棧變量 'STR' 已損壞。

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是0，調用_itoa(num, str, 16)將導致單個字符的字符串"0"。

在這種情況下，i將1，和str[i - 2] = a將寫前的字符串，從而破壞堆棧。

更一般地，範圍從0到15（含）的lParam的值將觸發該問題。