Do Go switch/cases fallthrough or not?

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南方客
南方客 2020-12-31 00:50

What happens when you reach the end of a Go case, does it fall through to the next, or assume that most applications don\'t want to fall through?

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  •  没有蜡笔的小新
    2020-12-31 01:18

    No, Go switch statements do not fall through by default. If you do want it to fallthrough, you must explicitly use a "fallthrough" statement. From the spec:

    In a case or default clause, the last non-empty statement may be a (possibly labeled) "fallthrough" statement to indicate that control should flow from the end of this clause to the first statement of the next clause. Otherwise control flows to the end of the "switch" statement. A "fallthrough" statement may appear as the last statement of all but the last clause of an expression switch.

    For example (sorry, I could not for the life of me think of a real example):

    switch 1 {
    case 1:
        fmt.Println("I will print")
        fallthrough
    case 0:
        fmt.Println("I will also print")
    }
    

    https://play.golang.org/p/va6R8Oj02z

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