Go - Dereferencing Pointer

A pointer is a powerful feature in the Golang programming language that allows you to work with the memory addresses.

In Golang, Dereferencing a pointer means accessing the value stored at the memory address pointer is pointing to. This concept is important in Golang as it enables you to optimize performance, share data between functions without copying, and manipulate data.

To declare a pointer, we use the * operator, and to get the memory address of a variable, we can use &(AND) operator.

Following is the way to declare a pointer and assign the memory address for Golang Deferencing Pointers

• var p *int (declares a pointer to an integer)
• p = &x (assigns the memory address of x to the pointer p)
• *p (dereferences the pointer to access the value stored at the memory address)

The Pointers themselves do not have parameters or return values, but functions that use pointers can have parameters and return values involving pointers.

Basic Dereferencing Pointers

Here, we declare an integer variable x and a pointer p that stores the memory address of x. By dereferencing the pointer p, we can access the value of x. So, we can modify the value of x by changing the value stored at the memory address pointed to by p.

Example

package main
import "fmt"

func main() {
   var x int = 64   
   var p *int        
   p = &x          

   fmt.Println("Value of x=", x)
   fmt.Println("Address of x=", &x)
   fmt.Println("Value of p=", p)
   fmt.Println("Dereferenced value of p=", *p)
   *p = 21 
   fmt.Println("New value of x=", x)
}

Output

Following is the output of the above program

Value of x= 64
Address of x= 0xc000124010
Value of p= 0xc000124010
Dereferenced value of p= 64
New value of x= 21

Dereferencing Struct Pointers

When you have a pointer to a struct, you can use the * operator or the shorthand -> syntax to access the struct's fields.

Example

package main
import "fmt"

type Student struct {
   name string
   age  int
}

func main() {
   p := &Student{"Indu", 18}
   fmt.Println("Name=", p.name)
   fmt.Println("Age=", (*p).age)
}

Output

Following is the output of the above program

Name= Indu
Age= 18

Passing and Dereferencing Pointers in Functions

Functions can take pointers as parameters and dereference them to modify the original values.

Example

package main
import "fmt"

func updateValue(val *int) {
   *val = 100
}

func main() {
   num := 25
   updateValue(&num)
   fmt.Println("Updated Value=", num)
}

Output

Following is the output of the above program

Updated Value= 100