donglun1020 2018-03-23 02:17
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Golang的Int标志和时间。

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I'm getting an invalid operation: *timeout * time.Second (mismatched types int and time.Duration) error when trying to run something similar to this

timeout := flag.Int("timeout", 30, "The time limit for answering questions.")
flag.Parse()
timeoutCh := time.After(*timeout * time.Second)

Just to be sure, I checked the type of *timeout using reflect.TypeOf() and it is in fact an int. But if I do timeoutCh := time.After(30 * time.Second) or use any other int value the code works.

What am I missing here?

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  • dousilie9522 2018-03-23 02:30
    关注
    timeoutCh := time.After(time.Duration(*timeout) * time.Second)
    

    You have to convert *timeout which is type int to type time.Duration. The reason why time.After(30 * time.Second) works is that 30 is untyped and is converted to the type of time.Second which is time.Duration. See https://golang.org/ref/spec#Operators. Similarly this code works

    x := uint(42)
    if x == 42 {
        println("works!")
    }
    

    but this code won't compile

    x := uint(42)
    y := 42 // defaults to type int
    if x == y {
        println("this won't complile!")
    }
    
    本回答被题主选为最佳回答 , 对您是否有帮助呢?
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