Pointers To Pointers | Pointers

Introduction

In Go programming, pointers are variables that store the memory address of another variable. A pointer to a pointer is a variable that stores the address of another pointer variable. This concept can be particularly useful in scenarios where you need to manage dynamic memory or pass a pointer to a function that modifies the pointer's target.

Basic Concept

To understand pointers to pointers, it's essential first to understand pointers. A pointer is declared using the * operator, and the address of a variable is obtained using the & operator. Consider the following example:

var a int = 10
var p *int = &a

In this example, p is a pointer to an integer variable a. Now, to create a pointer to this pointer p, you use an additional * operator:

var pp **int = &p

Working with Pointers to Pointers

Let's delve deeper into an example where we declare and manipulate pointers to pointers. Consider the following Go code:


                    package main


                    import "fmt"


                    func main() {

                         // Declare an integer variable

                         var a int = 10


                         // Declare a pointer to an integer variable

                         var p *int = &a


                         // Declare a pointer to a pointer to an integer variable

                         var pp **int = &p


                         // Print the values and addresses

                         fmt.Println("Value of a:", a)

                         fmt.Println("Address of a:", &a)

                         fmt.Println("Value of p (address of a):", p)

                         fmt.Println("Address of p:", &p)

                         fmt.Println("Value of pp (address of p):", pp)

                         fmt.Println("Dereferenced value of pp (value of p):", *pp)

                         fmt.Println("Double dereferenced value of pp (value of a):", **pp)

                    }

When you run this program, the output will be:

Value of a: 10
Address of a: 0xc0000140b0
Value of p (address of a): 0xc0000140b0
Address of p: 0xc00000e018
Value of pp (address of p): 0xc00000e018
Dereferenced value of pp (value of p): 0xc0000140b0
Double dereferenced value of pp (value of a): 10

Practical Use Cases

Pointers to pointers are useful in various scenarios, such as:

Managing dynamic memory.
Passing a pointer to a function and modifying the original pointer's target within the function.
Creating complex data structures like linked lists and trees.

Consider a scenario where you want to modify the target of a pointer inside a function:


                    package main


                    import "fmt"


                    func modifyPointer(pp **int) {

                         var newValue int = 20

                         *pp = &newValue

                    }


                    func main() {

                         var a int = 10

                         var p *int = &a


                         fmt.Println("Before modification:")

                         fmt.Println("Value of a:", a)

                         fmt.Println("Value of p (address of a):", p)

                         fmt.Println("Dereferenced value of p:", *p)


                         modifyPointer(&p)


                         fmt.Println("After modification:")

                         fmt.Println("Value of a:", a)

                         fmt.Println("Value of p (address of newValue):", p)

                         fmt.Println("Dereferenced value of p:", *p)

                    }

In this example, the function modifyPointer modifies the pointer p to point to a new integer variable newValue.

Before modification:
Value of a: 10
Value of p (address of a): 0xc0000140b0
Dereferenced value of p: 10

After modification:
Value of a: 10
Value of p (address of newValue): 0xc0000140b8
Dereferenced value of p: 20

Conclusion

Pointers to pointers are a powerful feature in Go programming, enabling more complex memory management and data manipulation. Understanding this concept can significantly enhance your ability to work with dynamic data structures and improve the efficiency of your programs.

Pointers to Pointers in Go Programming

Introduction

Basic Concept

Working with Pointers to Pointers

Practical Use Cases

Conclusion