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64 lines
1.3 KiB
Go
64 lines
1.3 KiB
Go
// _Switch statements_ express conditionals across many
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// branches.
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package main
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import (
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"fmt"
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"time"
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)
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func main() {
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// Here's a basic `switch`.
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i := 2
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fmt.Print("Write ", i, " as ")
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switch i {
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case 1:
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fmt.Println("one")
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case 2:
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fmt.Println("two")
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case 3:
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fmt.Println("three")
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}
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// You can use commas to separate multiple expressions
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// in the same `case` statement. We use the optional
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// `default` case in this example as well.
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switch time.Now().Weekday() {
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case time.Saturday, time.Sunday:
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fmt.Println("It's the weekend")
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default:
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fmt.Println("It's a weekday")
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}
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// `switch` without an expression is an alternate way
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// to express if/else logic. Here we also show how the
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// `case` expressions can be non-constants.
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t := time.Now()
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switch {
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case t.Hour() < 12:
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fmt.Println("It's before noon")
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default:
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fmt.Println("It's after noon")
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}
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// A type `switch` compares types instead of values. You
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// can use this to discover the type of an interface
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// value. In this example, the variable `t` will have the
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// type corresponding to its clause.
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whatAmI := func(i interface{}) {
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switch t := i.(type) {
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case bool:
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fmt.Println("I'm a bool")
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case int:
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fmt.Println("I'm an int")
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default:
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fmt.Printf("Don't know type %T\n", t)
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}
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}
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whatAmI(true)
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whatAmI(1)
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whatAmI("hey")
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}
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