🧷 Go Dereferencing Pointer – Access and Modify Values via Address (2025 Guide)

🧲 Introduction – What Is Dereferencing in Go?

In Go, dereferencing means accessing or modifying the value stored at a memory address pointed to by a pointer. Using the * operator, you can read or update the actual value instead of working with a copy. Dereferencing is essential for pointer-based operations like in-place modification, struct manipulation, and reference sharing.

🎯 In this section, you’ll learn:

• How to dereference a pointer in Go
• Read and update values via pointers
• Work with structs, arrays, and functions
• Best practices and error prevention

✅ Basic Syntax – Dereferencing an int Pointer

x := 10
p := &x         // pointer to x
fmt.Println(*p) // dereference pointer: Output → 10

✅ *p reads the value stored at the address held by p.

🔄 Modify Value via Dereferencing

*p = 20
fmt.Println(x) // Output → 20

✅ Changing *p also updates the value of x, since p points to x.

🧩 Example – Dereferencing Struct Pointers

type Person struct {
    Name string
}

p := Person{Name: "Alice"}
ptr := &p

(*ptr).Name = "Bob"
fmt.Println(p.Name) // Output → Bob

✅ You can access fields through (*ptr).Field or shorthand:

ptr.Name = "Charlie" // Same as (*ptr).Name

🔢 Dereferencing Pointer to Array

arr := [3]int{1, 2, 3}
p := &arr
(*p)[1] = 99

fmt.Println(arr) // Output → [1 99 3]

✅ Modifies the original array via its pointer.

🔁 In Functions – Dereferencing to Modify Arguments

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

x := 50
update(&x)
fmt.Println(x) // Output → 100

✅ Dereferencing inside the function lets you modify the caller’s original variable.

⚠️ Common Mistakes to Avoid

📦 Summary Table – Pointer and Dereference

📌 Summary – Recap & Next Steps

Dereferencing lets you work with actual data via pointers, not just their copies. It’s crucial for memory-safe, efficient Go programming in both simple and advanced use cases like structs, function arguments, and pointer arrays.

🔍 Key Takeaways:

• Use *p to read or write the value a pointer references
• * is the dereference operator
• Use in structs, arrays, functions, and pointer chains
• Always check for nil pointers before dereferencing

⚙️ Next: Explore Pointer Receivers in Methods or Go Interfaces with Pointer Types.

❓ FAQs – Go Dereferencing Pointer

❓ What does *p mean in Go?
✅ It dereferences the pointer p, i.e., gets the value stored at the address.

❓ Can I use *p = value to change the original variable?
✅ Yes. This modifies the value at the referenced memory location.

❓ Is * used for both declaration and dereferencing?
✅ Yes, but in different contexts:

• *int declares a pointer to int
• *p accesses the value from a pointer

❓ Can I dereference nil in Go?
❌ No. It will cause a runtime panic. Always check before dereferencing.

❓ How do I dereference a struct pointer?
✅ Use (*p).Field or the shorthand p.Field.