将switch语句组合在一起？

Question

我可能在寻找一些东西,但在C++中是否有一种简单的方法可以将案例分组在一起而不是单独写出来？我记得基本上我可以做到:

SELECT CASE Answer
CASE 1, 2, 3, 4

C++中的示例(对于那些需要它的人):

#include <iostream.h>
#include <stdio.h>
int main()
{
   int Answer;
   cout << "How many cars do you have?";
   cin >> Answer;
   switch (Answer)                                      
      {
      case 1:
      case 2:
      case 3:
      case 4:
         cout << "You need more cars. ";
         break;                                        
      case 5:
      case 6:
      case 7:
      case 8:
         cout << "Now you need a house. ";
         break;                                        
      default:
         cout << "What are you? A peace-loving hippie freak? ";
      }
      cout << "\nPress ENTER to continue... " << endl;
      getchar();
      return 0;
}

Answer 1

AFAIK所能做的就是省略返回以使C++中的东西更紧凑:

switch(Answer)
{
    case 1: case 2: case 3: case 4:
        cout << "You need more cars.";
        break;
    ...
}

(当然,您也可以删除其他退货.)

Answer 2

你当然可以.

您可以使用大小写x ... y作为范围

例:

#include <iostream.h>
#include <stdio.h>
int main()
{
   int Answer;
   cout << "How many cars do you have?";
   cin >> Answer;
   switch (Answer)                                      
      {
      case 1 ... 4:
         cout << "You need more cars. ";
         break;                                        
      case 5 ... 8:
         cout << "Now you need a house. ";
         break;                                        
      default:
         cout << "What are you? A peace-loving hippie freak? ";
      }
      cout << "\nPress ENTER to continue... " << endl;
      getchar();
      return 0;
}

确保在编译器中启用了"-std = c ++ 0x"标志

Answer 3

不,但你可以使用if- else if- else链来实现相同的结果:

if (answer >= 1 && answer <= 4)
  cout << "You need more cars.";
else if (answer <= 8)
  cout << "Now you need a house.";
else
  cout << "What are you? A peace-loving hippie freak?";

您可能还想处理0辆汽车的情况,然后也可能通过抛出异常来处理负数车辆的意外情况.

PS:我已经重命名Answer为answer因为用大写字母启动变量被认为是不好的风格.

作为旁注,像Python这样的脚本语言允许良好的if answer in [1, 2, 3, 4]语法,这是实现您想要的灵活方式.

Answer 4

你可以这样使用：

case 4: case 2:
 {
   //code ...
 }

适合使用 4 或 2 个开关盒。

Answer 5

您的示例与构造一样简洁switch。

Answer 6

您无法删除关键字case.但是你的例子可以像这样写得更短:

switch ((Answer - 1) / 4)                                      
{
   case 0:
      cout << "You need more cars.";
      break;                                        
   case 1:
      cout << "Now you need a house.";
      break;                                        
   default:
      cout << "What are you? A peace-loving hippie freak?";
}