golang deep pointer example

basic1.go

package main

import (

	"fmt"
)
func increment(ptr *int) {
	*ptr = *ptr + 1
}

func main() {
	val :=5
	increment(&val)
	fmt.Println("The incremented val is given below:")
	fmt.Println(val)
}

//--------------------------------

struct.go

package main

import (

	"fmt"
)


// https://go.dev/play/p/TmrXMHKMjlt
// https://golangprojectstructure.com/pointer-variables-go-code-examples/

type Server struct {
	name string
}

// setName if * pointer = ok
func (server *Server) setName(newName string) {
	server.name = newName
}

type Client struct {
	name string
}

// setName if not * pointer = not change
func (client Client) setName(newName string) {
	client.name = newName
}

func main() {
	fmt.Println("/////---------- example 1 only struct access")
	server := Server{
		name: "John",
	}

	fmt.Println(server.name)

	fmt.Println("/////---------- example 2 --changed because pointer ")
	serverPointer := Server{
		name: "John",
	}

	fmt.Println(serverPointer.name)

	serverPointer.setName("Jack") // changed

	fmt.Println(serverPointer.name)

	fmt.Println("/////----------  example 3 (client struct) not change because is not pointer ")

	client := Client{
		name: "John",
	}

	fmt.Println(client.name)

	client.setName("Jack")

	fmt.Println(client.name)

}

swap3.go

package main

import "fmt"

func main() {
	/* local variable definition */
	var a int = 100
	var b int = 200

	fmt.Printf("Before swap, value of a : %d\n", a)
	fmt.Printf("Before swap, value of b : %d\n", b)

	/* calling a function to swap the values.
	 * &a indicates pointer to a ie. address of variable a and
	 * &b indicates pointer to b ie. address of variable b.
	 */
	swap(&a, &b)

	fmt.Printf("After swap, value of a : %d\n", a)
	fmt.Printf("After swap, value of b : %d\n", b)
}
func swap(x *int, y *int) {
	var temp int
	temp = *x /* save the value at address x */
	*x = *y   /* put y into x */
	*y = temp /* put temp into y */
}