Structs in Go – Modeling Real-World Data

Learn how to use structs in Golang to represent real-world entities

In Golang, structs are used to model real-world entities — like a User, Book, or Product — by grouping related values together. This article breaks down how to define, use, and manipulate structs using practical examples.

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🔹 1. What Is a Struct?

A struct (short for “structure”) is a custom data type in Go that groups related variables (called fields) together under one name.

Think of it as a container for data that belongs together.

🧪 Defining a Struct

type Person struct {
    name string
    age  int
}

🔹 2. Creating Struct Instances

✅ Method 1: Named Fields

p1 := Person{name: "Amit", age: 30}

✅ Method 2: Positional Fields (not recommended for readability)

p2 := Person{"Rahul", 28}

✅ Method 3: Declare then Assign

var p3 Person
p3.name = "Neha"
p3.age = 25

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🔹 3. Accessing and Updating Fields

fmt.Println(p1.name) // Output: Amit
p1.age = 31
fmt.Println(p1.age) // Output: 31

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🔹 4. Passing Structs to Functions

Structs can be passed by value or by pointer.

📦 By Value (Copy):

func printPerson(p Person) {
    fmt.Println(p.name, p.age)
}

🪝 By Pointer (Modify Original):

func birthday(p *Person) {
    p.age++
}

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🔹 5. Nested Structs

You can define structs inside other structs.

type Address struct {
    city  string
    state string
}

type Employee struct {
    name    string
    age     int
    address Address
}

🧪 Example:

emp := Employee{
    name: "Sita",
    age:  29,
    address: Address{
        city:  "Bangalore",
        state: "Karnataka",
    },
}
fmt.Println(emp.name, "from", emp.address.city)

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🔹 6. Anonymous Structs (Quick Use)

temp := struct {
    brand string
    year  int
}{
    brand: "Toyota",
    year:  2020,
}

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🔹 7. Structs vs Maps (When to Use What)

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🧪 Try It Yourself

1. Create a Book struct with title, author, and price

2. Write a function that prints the book details

3. Add a nested Publisher struct inside the Book struct

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✅ Summary

• Structs group related data into one clean type

• You can access, update, and pass them to functions

• Nested structs allow you to model real-world hierarchies

• Use structs when the shape of your data is known and fixed

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📘 Next: “Methods in Go – Attaching Behavior to Structs”
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