golang：类型断言基本使用方法

Posted 2021-10-28 live4m

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package main

import "fmt"

func f(i interface{}) {
	s := i.(string) //转化为string,如果转化失败会报panic
	fmt.Println(s)
}
func main() {
	f("100")
	f(1)
}
/*
结果:
100
panic: interface conversion: interface {} is int, not string

goroutine 1 [running]:
main.f({0x5b44a0, 0x5e5e50})
        g:/repos/go/test/main.go:6 +0x8a
main.main()
        g:/repos/go/test/main.go:11 +0x3a
exit status 2
*/

package main

import "fmt"

func f(i interface{}) {
	s, ok := i.(string) //ok是bool,表示是否转化成功
	if !ok {
		fmt.Println("转化失败")
		return
	}
	fmt.Println(s)
}
func main() {
	f("100")
	f(1)
}

package main

import "fmt"

func f(i interface{}) {
	switch t := i.(type) {//配合switch-case使用
	case string:
		fmt.Println("string", t)
	case int:
		fmt.Println("int", t)
	}
}
func main() {
	f("100")
	f(1)
}

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