package options
type IPeople interface {
 GetName() string
}
type IPeople2 interface {
 GetName() string
 GetAge() int
}
package main
import (
 "fmt"
 "options"
)
type person struct {
 name string
}
func (p *person) GetName() string {
 return p.name
}
type person2 struct {
 name string
 age int
}
func (p *person2) GetName() string {
 return p.name
}
func (p *person2) GetAge() int {
 return p.age
}
func main() {
 //p不可以轉化為options.IPeople2接口，沒有實現options.IPeople2接口中的GetAge()
 var p options.IPeople = person{"jack"}
 if p2, ok := p.(options.IPeople2); ok {
 fmt.Println(p2.GetName(), p2.GetAge())
 } else {
 fmt.Println("p不是Ipeople2接口類型")
 }
 //p2可以轉化為options.IPeople接口，因為實現了options.IPeople接口的所有方法
 var p2 options.IPeople2 = person2{"mary", 23}
 if p, ok := p2.(options.IPeople); ok {
 fmt.Println(p.GetName())
 }
 
 var pp options.IPeople = person{"alen"}
 if pp2, ok := pp.(*person); ok {
 fmt.Println(pp2.GetName()) //pp接口指向的對象實例是否是*person類型,*不能忘
 }
   switch pp.(type) {
 case options.IPeople:
 fmt.Println("options.IPeople") //判斷接口的類型
 case options.IPeople2:
 fmt.Println("options.IPeople2")
 default:
 fmt.Println("can't found")
  }
  var ii interface{} = 43 //默認int類型
  switch ii.(type) {
 case int:
 fmt.Println("int")
 default:
 fmt.Println("can't found")
  }
}

var v1 interface{} = 1   
  var v2 interface{} = "abc"  
  var v3 interface{} = 2.345
  var v4 interface{} = make(map[..]...)
  ....

package main 
  import "fmt"
 
  //空接口可以接受任何值
  //interface { }
 
  func main() {
    var v1 interface{ }
    v1 = 6.78
 
//賦值一個變量v判斷其類型是否為float64，是則為真，否則，為假
    if v, ok := v1.(float64);ok{
      fmt.Println(v, ok)
    }else {
      fmt.Println(v,ok)
    } 
  }

package main 
import "fmt"
 
//空接口可以接受任何值
//interface { }
 
func main() {
  var v1 interface{ }
  v1 = "張三"
 
  switch v1.(type) {
  case float32:
 
  case float64:
    fmt.Println("this is float64 type")
  case string:
    fmt.Println("this is string type") 
  } 
}