Pointers in Go

pointers.go

package main

import (
	"fmt"
)

func main() {
	// Create variable i that holds an integer value
	var i int
	
	// Create variable p that can hold the memory address of an integer variable
	var p *int

	fmt.Println("Initially:")
	fmt.Printf("i: %v\n", i)
	fmt.Printf("*p: %v\n", "This would generate a `runtime error: invalid memory address or nil pointer dereference`")
	fmt.Printf("&i: %v\n", &i)
	fmt.Printf("p: %v\n", p)

	// Set the value of p to the memory address of variable i
	p = &i

	fmt.Println()
	fmt.Println("After `p = &i`:")
	fmt.Printf("i: %v\n", i)
	fmt.Printf("*p: %v\n", *p)
	fmt.Printf("&i: %v\n", &i)
	fmt.Printf("p: %v\n", p)

	// Set the value of i to the integer 42
	i = 42

	fmt.Println()
	fmt.Println("After `i = 42`:")
	fmt.Printf("i: %v\n", i)
	fmt.Printf("*p: %v\n", *p)
	fmt.Printf("&i: %v\n", &i)
	fmt.Printf("p: %v\n", p)

	// Change the value of the integer held at the memory address that p holds
	*p = 142

	fmt.Println()
	fmt.Println("After `*p = 142`:")
	fmt.Printf("i: %v\n", i)
	fmt.Printf("*p: %v\n", *p)
	fmt.Printf("&i: %v\n", &i)
	fmt.Printf("p: %v\n", p)
}