这个do-while循环为什么不起作用？

Question

有人可以向我解释为什么这个do-while循环无法正常工作吗？

该程序请求的表达，则该程序输出的正确答案。显示答案后，程序会询问用户是否要执行另一个计算。但是，即使用户指出他们不想再次执行计算，程序仍会循环。

#include <iostream> 
#include <cmath> 
#include <string> 
using namespace std; 

int main() { 

    float num_one; 
    float num_two; 
    char user_operator_one; 
    char repeat; 

    cout << "This is a very simple calculator." << endl; 

    cout << "Please enter your expression: "; 
    cin >> num_one >> user_operator_one >> num_two; 
    cout << "\n\n"; 

    do 
     { 
      switch (user_operator_one) 
       { 
       case '+': 
        cout << num_one << "+" << num_two << "=" << num_one + num_two << endl; 
        break; 

       case '-': 
        cout << num_one << "-" << num_two << "=" << num_one - num_two << endl; 
        break; 

       case '*': 
        cout << num_one << "*" << num_two << "=" << num_one * num_two << endl; 
        break; 

       case '/': 
        if (num_two == 0) { 
         cout << "Answer is undefined" << endl; 
        } 
        cout << num_one << "/" << num_two << "=" << num_one/num_two << endl; 
        break; 

       default: 
        cout << user_operator_one << "is an unknown operation." << endl; 
        break; 
       } 

      cout << "Would you like to perform another operation (enter a 1 for yes, 0 for no.)"; 
      cin >> repeat; 
     } while (repeat == 1); 
} 

Answer 1

repeat是char，你应该测试对'1'：否则

//... 
while (repeat == '1'); 

，你正在测试针对的十进制数值1，这在ASCII表相当于一个SOH或者“标题开始“字符，这是不可打印的。

此外，您需要将您的请求输入是内循环的do部分：

do 
{ 
    cout << "Please enter your expression: "; 
    cin >> num_one >> user_operator_one >> num_two; 
    cout << "\n\n"; 
    // ... 

Answer 2

您可以更改

char repeat; 

到

int repeat;