Question

我正在尝试进行模数运算。我要求用户输入两个数字，因为模数只适用于整数，我有一个while循环检查输入是否为整数。然后while循环要求用户重新输入这两个数字。但是while循环不断重复，并且不允许用户重新输入数字。这样做有什么用呢？

#include <iostream>
using namespace std;

int Modulus (int, int,struct Calculator);

struct Calculator
{
    int per_numb1, per_numb2;
    int per_Result; };

int main () 
{ 
    Calculator Operation1;

    cout << "\nPlease enter the first number to calculate as a modulus: "; 
    cin >> Operation1.per_numb1; 

    cout << "\nPlease enter the second number to calculate modulus: "; 
    cin >> Operation1.per_numb2; 

while ( !( cin >> Operation1.per_numb1)  ||   !( cin >> Operation1.per_numb2))
{ 

        cout << "\nERROR\nInvalid operation \nThe first number or second number   must be an integer"; 
        cout << "\n\nPlease re-enter the first number to begin Modulus: "; 
        cin >> Operation1.per_numb1;  

        cout << "\nPlease re-enter the second number to begin Modulus: ";
        cin >> Operation1.per_numb2;
}





Operation1.per_Result = Modulus(Operation1.per_numb1, Operation1.per_numb2, Operation1); 

cout << "\nThe result  is: " << Operation1.per_Result << endl;

}

int Modulus (int n1, int n2, struct Calculator)
{
    int Answer; 

    Answer = n1 % n2; 

    return Answer; 
}

Answer 1

重构这样的事情：

 #include <iostream>
 #include <string>
 #include <limits>

 using namespace std;

 class Calculator
 {
 public:
     static int Modulus (int n1, int n2);
 };

 int Calculator::Modulus (int n1, int n2)
 {
     return n1 % n2; 
 }

 int getInt(string msg)
 {
     int aa;

     cout << msg;
     cin >> aa;
     while (cin.fail())
     {
         cin.clear();
         cin.ignore(std::numeric_limits<streamsize>::max(),'\n');
         cerr <<  "Input was not an integer!" << endl;
         cout << msg;
         cin >> aa;
     } 
     return aa;
 }

 int main () 
 { 
     int num1 = getInt("Enter first value: ");
     int num2 = getInt("Enter second value: ");
     int value = Calculator::Modulus(num1,num2);
     cout << "Answer:" << value << endl ;
 }

Answer 2

当输入解析失败时，无效的输入数据将保留在流中。你需要

通过调用cin.clear()清除流错误状态。
并跳过剩余的无效输入。

See the answer to this question.

C ++ -While循环在检查输入是否为整数时不断重复 -

2 个答案: