Question

#include <iostream>
using namespace std;

int main()
{
   float a, b, result;
   char operation, response;
   cin >> a >> operation >> b;
   switch(operation)
   {
   case '+':
         result = a + b;
         break;

   case '-':
         result = a - b;
         break;

   case '*':
         result = a * b;
         break;

   case '/':
         result = a / b;
         break;

   default:
         cout << "Invalid operation. Program terminated." << endl;
         return -1;
   }

   // Output result
   cout << "The result is " << result << endl;
   system("sleep 200");
   cout << "Do you want to make another opertaion? (Y/N)" << endl;
   cin >> response;
   if(response=='Y')
   {
    here
   }
   else if(response=='N')
   {
    cout << "The program will now close" << endl;
    system("sleep 500");
    return -1;
   }
   return 0;
}

如果写“here”这个词，我想插入一个代码，让你接受代码的开始。

Answer 1

您可以使用循环do... while(condition)

喜欢：

do{
    cin >> a >> operation >> b;
    switch(operation)
    {
...

    }

    // Output result
    cout << "The result is " << result << endl;
    system("sleep 200");
    cout << "Do you want to make another opertaion? (Y/N)" << endl;
    cin >> response;
}while(response=='Y');

如果响应不是'Y'，则循环结束，如果循环再次开始

Answer 2

尽管goto在C ++中非常不受欢迎，但确实存在。就像装配一样，你在你的代码中加上一个标签，然后告诉它跳过＆＃39;使用goto。但是，跳转在程序集中的工作方式相同，这可能会使您从所有循环中突破到跳转到的位置。

#include <iostream>
using namespace std;

int main()
{
   label: 
   float a, b, result;
   char operation, response;
   cin >> a >> operation >> b;
//condensed for neatness

   // Output result
   cout << "The result is " << result << endl;
   system("sleep 200");
   cout << "Do you want to make another opertaion? (Y/N)" << endl;
   cin >> response;
   if(response=='Y')
   {
    goto label;
   }
   else if(response=='N')
   {
    cout << "The program will no`enter code here`w close" << endl;
    system("sleep 500");
    return -1;
   }
   return 0;
}

大多数人会做的是使用do{}while(condition==true)循环或仅使用无限循环while(true)。

对于这个＆＃39; neater＆＃39;代码，你要做的是

#include <iostream>
using namespace std;

int main()
{
   do{
   float a, b, result;
   char operation, response;
   cin >> a >> operation >> b;
   //condensed for neatness 


// Output result


   cout << "The result is " << result << endl;
   system("sleep 200");
   cout << "Do you want to make another opertaion? (Y/N)" << endl;
   }while(cin.get() == 'Y');


    cout << "The program will no`enter code here`w close" << endl;
    system("sleep 500");
    return -1;

   return 0;
}

如果从另一个位置调用它，我强烈建议使用do而不是goto，因为它可能会导致问题。

goto唯一真正的问题是它不优雅并且使代码难以阅读。您应该尽可能使用循环并返回，如果您没有其他方法可以使此工作达到最佳效果，则只能使用goto。

某种用于C ++的'goto'函数

2 个答案: