Passing values vs pointers in Go - Hands-On Comparison

Passing values vs pointers

📖 Scenario: Imagine you have a simple program that manages a person's age. You want to understand how changing the age inside a function affects the original age variable. This will help you learn the difference between passing values and passing pointers in Go.

🎯 Goal: You will create a program that shows how passing a value to a function does not change the original variable, but passing a pointer to a function allows you to change the original variable.

📋 What You'll Learn

Create a variable age with the value 30

Create a function increaseAgeValue that takes an int parameter and increases it by 1

Create a function increaseAgePointer that takes a pointer to an int and increases the value it points to by 1

Call both functions with the age variable and observe the difference

Print the value of age after each function call

💡 Why This Matters

🌍 Real World

Understanding passing by value and by pointer helps when writing programs that manage data efficiently, like updating user profiles or handling large data structures.

💼 Career

Many Go programming jobs require knowledge of pointers to write efficient and correct code, especially in system programming, backend services, and performance-critical applications.

1

Create the initial variable

Create a variable called age and set it to 30.

Go

age := 0
// Your code here

Hint

Use age := 30 to create the variable.

2

Create the functions to increase age

Create two functions: increaseAgeValue that takes an int parameter called a and increases it by 1, and increaseAgePointer that takes a pointer to an int called a and increases the value it points to by 1.

Go

package main

import "fmt"

func main() {
    age := 30
}

// Your code here

Hint

Remember, to change the original variable, use a pointer parameter and dereference it with *.

3

Call the functions with the variable

Inside main, call increaseAgeValue with age, then call increaseAgePointer with the address of age using &age.

Go

package main

import "fmt"

func increaseAgeValue(a int) {
    a = a + 1
}

func increaseAgePointer(a *int) {
    *a = *a + 1
}

func main() {
    age := 30
    // Your code here
}

Hint

Call increaseAgeValue(age) and increaseAgePointer(&age) inside main.

4

Print the value of age after each function call

Add fmt.Println(age) after calling increaseAgeValue(age) and again after calling increaseAgePointer(&age) to show how the value changes.

Go

package main

import "fmt"

func increaseAgeValue(a int) {
    a = a + 1
}

func increaseAgePointer(a *int) {
    *a = *a + 1
}

func main() {
    age := 30
    increaseAgeValue(age)
    // Your code here
    increaseAgePointer(&age)
    // Your code here
}

Hint

Use fmt.Println(age) after each function call to see the difference.