Go — Structs

Basic struct

package main

import "fmt"

type Person struct {
    Name string
    Age  int
}

func main() {
    p1 := Person{Name: "Alice", Age: 30}
    p2 := Person{"Bob", 25}

    fmt.Println(p1.Name)
    fmt.Println(p2)
}

Nested structs

type Address struct {
    Street string
    City   string
    Zip    string
}

type Person struct {
    Name    string
    Age     int
    Address Address
}

func main() {
    p := Person{
        Name: "Alice",
        Age:  30,
        Address: Address{
            Street: "123 Main St",
            City:   "NYC",
            Zip:    "10001",
        },
    }

    fmt.Println(p.Address.City)
}

Struct methods

type Rectangle struct {
    Width, Height float64
}

func (r Rectangle) Area() float64 {
    return r.Width * r.Height
}

func (r Rectangle) Perimeter() float64 {
    return 2 * (r.Width + r.Height)
}

func (r *Rectangle) Scale(factor float64) {
    r.Width *= factor
    r.Height *= factor
}

func main() {
    r := Rectangle{Width: 5, Height: 3}
    fmt.Println("Area:", r.Area())
    r.Scale(2)
    fmt.Println("Scaled area:", r.Area())
}

Anonymous structs

point := struct {
    X, Y int
}{X: 1, Y: 2}

fmt.Println(point)

Struct tags

type User struct {
    Name  string `json:"name" db:"user_name"`
    Email string `json:"email" db:"email"`
    Age   int    `json:"age,omitempty" db:"age"`
}

Best practices

• Use structs over maps for fixed data shapes
• Use pointer receivers for methods that modify state
• Use value receivers for read-only methods
• Keep structs small and focused

Mini Practice

Write Go code that:

1. Creates a Person struct with a method
2. Uses nested structs
3. Creates an anonymous struct
4. Demonstrates pointer vs value receivers

Up Next

In the next lesson, you'll learn about Pointers — memory addresses in Go.