Defining Custom Types with Structs

Snippet

Defining Custom Types with Structs

Structs are composite types that group together related fields. You define a struct using the `type` keyword, then create instances with brace initialization. Methods can be attached to structs using a receiver - here `(r Rectangle)` means the method belongs to Rectangle values. Pointers to structs are useful for mutation and are automatically dereferenced when accessing fields.

snippet.go
go
package main
 
import "fmt"
 
type Rectangle struct {
    Width  float64
    Height float64
}
 
func (r Rectangle) Area() float64 {
    return r.Width * r.Height
}
 
func main() {
    rect := Rectangle{Width: 10.5, Height: 4.2}
    fmt.Printf("Area: %.2f\n", rect.Area())
 
    ptr := &rect
    fmt.Printf("Width via pointer: %.2f\n", ptr.Width)
}

Breakdown

type Rectangle struct {

Defines a new struct type with Width and Height fields

func (r Rectangle) Area() float64 {

Method with value receiver attached to Rectangle

rect := Rectangle{Width: 10.5, Height: 4.2}

Creates instance using named field initialization

ptr := &rect

Creates a pointer to the rectangle

ptr.Width

Go automatically dereferences pointer to access field

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Defining Custom Types with Structs

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