您能以编程方式在交换案例中调用特定案例吗？

Question

I have a switch case that looks like this:

switch ( class.Function() )
{

    case firstThing:
    {

    }
        break;
    case secondThing:
    {
     //call third thing
     }
     break;
    case thirdThing:
    {

     }
     break;

    }

Is there any way to call a specific case in C / Objective-C?

Answer 1

不知道您为什么要这样做，但是在您的示例中，如果仅在case secondThing末尾省去了break语句，用户将继续执行后续的case语句，直到遇到中断为止。

Answer 2

It seems what you're trying to implement is switch statement fall through. By leaving out the break statement after case #2, you will execute whatever code is in case #3. This may be what you want.

switch ( class.Function() )
{

    case firstThing:
    {

    }
        break;
    case secondThing:
    {
     //go to case 3
    }

    case thirdThing:
    {

    }
     break;

    }

Answer 3

In your particular example, you could use case fall through, but that is not a solution to your question in general, and if there is code specific to secondThing , it can lead to confusion and could be considered bad practice.

switch ( class.Function() )
{
    case firstThing:
    {

    }
    break;

    case secondThing:
    case thirdThing:
    {

    }
    break;
}

If you simply implement the body of each case as a function, then that is perhaps the more general solution:

switch( class.Function() )
{
    case firstThing:  something();                     break;
    case secondThing: anotherThing(); oneMoreThing();  break;
    case thirdThing:  oneMoreThing();                  break;
}