使用数组和运行时检查失败＃2-S，Visual Studio的C++

Question

我计算数字的发生，结果是准确的，右：

#include <iostream> 
using namespace std; 
const int max = 51; 

int main() 
{ 
    int num = 0; 
    int array[max] = { 0 }; 
    cout << "Enter interger number from 0 to 50 and type in -1 to show occurence:"; 
    while (num!=-1) 
    { 
     cin >> num; 
     array[num] = array[num]+1; 
    } 
    cout << "all entered number are:" << endl; 
    cout << "Number\tFrequency" << endl; 
    for (num = 0; num < max; num++) 
    { 
     if (array[num]>0) 
     { 
      cout << num <<"\t"<< array[num] << endl; 
     } 
    } 
    return 0; 
} 

为什么在Visual Studio总是通知我的以下：

运行时检查失败＃2-S，

Answer 1

当num变量变为-1时，您正在访问数组元素超出范围（array[-1]），从而调用undefined behavior，这会导致堆栈损坏。如果您接受大于50的输入，则会发生同样的情况。确保num变量保持在0..50边界内。引入另一个变量来控制逻辑和while循环：

int controlvar = 0; 
int num = 0; 
int array[max] = { 0 }; 
std::cout << "Enter integer number from 0 to 50 and type in -1 to show occurence: "; 
while (controlvar != -1) 
{ 
    std::cin >> controlvar; 
    if (controlvar >= 0 && controlvar <= 50){ 
     num = controlvar; 
     array[num] = array[num] + 1; 
    } 
}