C++宏 - for循环出错

Question

我有以下代码的问题.第一个for循环打印数组中的所有元素,而第二个for循环不打印任何东西.为什么？

#define TOTAL_ELEMENTS (sizeof(array) / sizeof(array[0]))                      
int array[] = {23,34,12,17,204,99,16};                                         

int main()                                                                     
{                                                                              
    int d;                                                                     
    //Working                                                               
    for(d=0;d < (TOTAL_ELEMENTS);d++)                                          
    {                                                                       
        cout << array[d] <<endl;                                               
    }                                                                       

    //This does not work. Why does this code fail? Isn't it same as the one above?
    //If I assing TOTAL_ELEMENTS to a variable and then use that in for loop (below), it works! Why?                                                  
    for(d=-1; d < (TOTAL_ELEMENTS);d++)                                        
    {                                                                       
        cout << array[d + 1] << endl;                                              
    }                                                                       
}      

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Answer 1

sizeof运算符返回一个size_t值,这是一个无符号整数类型,所以在这个循环中:

for(d=-1; d < (TOTAL_ELEMENTS);d++)

-1 被转换为非常大的无符号整数值.