使用數組和運行時檢查失敗＃2-S，Visual Studio的C++

Question

我計算數字的發生，結果是準確的，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; 
} 

爲什麼在Visual Studio總是通知我的以下：

運行時檢查失敗＃2-S，

Answer 1

當num變量變爲-1時，您正在訪問數組元素超出範圍（array[-1]），從而調用undefined behavior，這會導致堆棧損壞。如果您接受大於50的輸入，則會發生同樣的情況。確保num變量保持在0..50邊界內。引入另一個變量來控制邏輯和while循環：

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; 
    } 
}