golang 结构体方法 有无指针

package main

import "fmt"

type Node struct {
    Val string
}


func (n Node) Put(str string) {
    n.Val = str
}

func (n Node) Pull() string {
    return n.Val
}

func main() {
    n := Node{}
    n.Put("1")
    fmt.Println(n.Pull())
}

//////
result -> 空 

package main

import "fmt"

type Node struct {
    Val string
}


func (n *Node) Put(str string) {
    n.Val = str
}

func (n *Node) Pull() string {
    return n.Val
}

func main() {
    n := Node{}
    n.Put("1")
    fmt.Println(n.Pull())
}


/////////
result -> 1