case使用例子

case使用例子

  1. #include <iostream>
  2. using namespace std;
  3. int main()
  4. {
  5. char choice;
  6. cout << "Enter A, B, or C: ";
  7. cin >> choice;
  8. switch (choice)
  9. {
  10. case ‘A‘ :
  11. cout<< "You entered A. \n";
  12. case ‘B‘ :
  13. cout << "You entered B. \n";
  14. case ‘C‘ :
  15. cout << "You entered C.\n";
  16. default:
  17. cout << "You did not enter A, B, or C!\n";
  18. }
  19. return 0;
  20. }

程序运行结果:

Enter A, B, or C: A
You entered A.
You entered B.
You entered C.
You did not enter A, B, or C!

在没有 break 语句之后,此程序“渎职”放行了匹配 case 表达式下面的所有语句,使它们都被执行了,但有时这样的效果也正是程序员想要的,如下面所示:

  1. #include <iostream>
  2. using namespace std;
  3. int main()
  4. {
  5.     char feedGrade;
  6.     //Get the desired grade of feed
  7.     cout << "Our dog food is availablein three grades:\n";
  8.     cout << "A, B, and C. Which do you want pricing for? ";
  9.     cin >> feedGrade;
  10.     // Find and display the price
  11.     switch(feedGrade)
  12.     {
  13.      case ‘a‘:
  14.       case ‘A‘:
  15.        cout << "30 cents per pound.\n";
  16.         break;
  17.       case ‘b‘:
  18.       case ‘B‘:
  19.        cout << "30 cents per pound.\n";
  20.         break;
  21.       case ‘c‘:
  22.       case ‘C‘:
  23.         cout << "15 cents per pound.\n";
  24.         break;
  25.       default :
  26.         cout << "That is an invalid choice.\n";
  27.     }
  28.     return 0;
  29. }

程序输出结果:

Our dog food is available in three grades:
A, B, and C. Which do you want pricing for? b
20 cents per pound.

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case使用例子

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