What is the difference between passing a struct and pointer of the struct, are they not both pointers?

Question

For example

var myStructRef *Vertex
var myStruct Vertex
myStructRef = &Vertex{2, 3}
myStruct = Vertex{2, 3}

fmt.Println(myStructRef)
fmt.Println(myStruct)
c         


        

Answer 1

Passing struct to function argument makes copy of values. And passing pointer of struct doesn't. So passing struct can't update field value.

package main

import (
    "fmt"
)

type Foo struct {
    value int
}

func PassStruct(foo Foo) {
    foo.value = 1
}

func PassStructPointer(foo *Foo) {
    foo.value = 1
}

func main() {
    var foo Foo

    fmt.Printf("before PassStruct: %v\n", foo.value)
    PassStruct(foo)
    fmt.Printf("after PassStruct: %v\n", foo.value)

    fmt.Printf("before PassStructPointer: %v\n", foo.value)
    PassStructPointer(&foo)
    fmt.Printf("after PassStructPointer: %v\n", foo.value)
}

https://play.golang.org/p/AM__JwyaJa