Structs in Go #

A struct is a composite data type that groups together variables under a single name. These variables, known as fields, can be of different types. Structs are a fundamental concept in Go for creating complex data structures.

Defining and Using Structs #

You can define a struct using the type and struct keywords. Once a struct type is defined, you can create instances (values) of that struct.

package main
import "fmt"
// Define a struct type
type Person struct {
 Name string
 Age int
}
func main() {
 // Create an instance of the Person struct
 p1 := Person{Name: "Alice", Age: 30}
 fmt.Println(p1)
 // Accessing struct fields
 fmt.Println("Name:", p1.Name)
 fmt.Println("Age:", p1.Age)
 // You can also create a pointer to a struct
 p2 := &Person{Name: "Bob", Age: 25}
 fmt.Println(p2.Name) // Go automatically dereferences the pointer
}

Methods on Structs #

Go allows you to define methods on struct types. A method is a function with a special receiver argument. The receiver appears in its own argument list between the func keyword and the method name.

package main
import "fmt"
type Rectangle struct {
 Width, Height float64
}
// A method for the Rectangle struct
func (r Rectangle) Area() float64 {
 return r.Width * r.Height
}
func main() {
 rect := Rectangle{Width: 10, Height: 5}
 fmt.Println("Area:", rect.Area())
}

Embedding Structs #

Go does not provide inheritance in the traditional sense, but it does support composition through struct embedding. You can embed a struct within another struct to “inherit” its fields and methods.

package main
import "fmt"
type Engine struct {
 Horsepower int
}
func (e Engine) Start() {
 fmt.Println("Engine started.")
}
type Car struct {
 Engine // Embed the Engine struct
 Make string
 Model string
}
func main() {
 car := Car{
 Engine: Engine{Horsepower: 300},
 Make: "Toyota",
 Model: "Camry",
 }
 // The Car struct now has the fields and methods of Engine
 fmt.Println("Horsepower:", car.Horsepower)
 car.Start()
}

This is a powerful feature that allows for flexible and reusable code.

Key Features of Structs #

• Composition: Structs are the primary way to build complex data types in Go.
• Methods: You can define methods on structs to add behavior.
• Embedding: Structs can be embedded within other structs to promote code reuse.
• Value vs. Pointer Receivers: Methods can have either a value or a pointer receiver, which affects whether the method can modify the original struct.