the-way-to-go_ZH_CN/eBook/examples/chapter_11/empty_interface.go

package main

import "fmt"

var i = 5
var str = "ABC"

type Person struct {
	name string
	age	int
}

type Any interface{}

func main() {
	var val Any
	val = 5
	fmt.Printf("val has the value: %v\n", val)
	val = str
	fmt.Printf("val has the value: %v\n", val)
	pers1 := new(Person)
	pers1.name = "Rob Pike"
	pers1.age = 55
	val = pers1
	fmt.Printf("val has the value: %v\n", val)
	switch t := val.(type) {
		case int:
			fmt.Printf("Type int %T\n", t)
		case string:
			fmt.Printf("Type string %T\n", t)
		case bool:
   			fmt.Printf("Type boolean %T\n", t)
		case *Person:
   			fmt.Printf("Type pointer to Person %T\n", *t)
		default:
   			fmt.Printf("Unexpected type %T", t)
	}
}