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7.Switch.go
76 lines (65 loc) · 2.06 KB
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7.Switch.go
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/*
Title: 7.Switch.go
Author: OpenSource
Date: 2017-05-20
Description: For Study
Switch statements express conditionals across many branches.
*/
package main
import "fmt"
import "time"
func main() {
fmt.Println("7.Switch.go--------Start-----------")
fmt.Println("\n i := 2 switch i {} ")
// Here’s a basic switch.
i := 2
fmt.Print("Write ", i, " as ")
switch i {
case 1:
fmt.Println("One")
case 2:
fmt.Println("Two")
case 3:
fmt.Println("Three")
}
fmt.Println("\n switch time.Now().Weekday(){} ")
// You can use commas to separate multiple expressions in the same case statement.
// We use the optional default case in this example as well.
switch time.Now().Weekday() {
case time.Saturday, time.Sunday:
fmt.Println("It's the weekend")
default:
fmt.Println("It's a weekday")
}
fmt.Println("\n switch time.Now().Weekday(){}")
// switch without an expression is an alternate way to express if/else logic.
// Here we also show how the case expressions can be non-constants.
t := time.Now()
switch{
case t.Hour() < 12:
fmt.Println("It's before noon")
default:
fmt.Println("It's after noon")
}
fmt.Println("\n whatAmI := func(i interface{}){ switch t := i.(type){} } ")
// A type switch compares types instead of values.
// You can use this to discover the the type of an interface value.
// In this example, the variable t will have the type corresponding to its clause.
whatAmI := func(i interface{}){
switch t := i.(type){
case bool:
fmt.Println("I'm a bool")
case int:
fmt.Println("I'm an int")
default:
fmt.Println("Don't know type %T \n",t)
}
}
fmt.Println("whatAmI(true)")
whatAmI(true)
fmt.Println("whatAmI(1)")
whatAmI(1)
fmt.Println("whatAmI(\"hey\")")
whatAmI("hey")
fmt.Println("7.Switch.go--------End-----------")
}