Try It Yourself - SyntaxStudy Editor

HTML / CSS / JS

package main

import (
    "fmt"
    "math"
)

type Point struct {
    X, Y float64
}

// Value receiver — does not modify the struct
func (p Point) Distance(q Point) float64 {
    dx := p.X - q.X
    dy := p.Y - q.Y
    return math.Sqrt(dx*dx + dy*dy)
}

type Rectangle struct {
    TopLeft     Point
    BottomRight Point
}

// Pointer receiver — modifies the struct
func (r *Rectangle) Scale(factor float64) {
    r.BottomRight.X = r.TopLeft.X + (r.BottomRight.X-r.TopLeft.X)*factor
    r.BottomRight.Y = r.TopLeft.Y + (r.BottomRight.Y-r.TopLeft.Y)*factor
}

func (r Rectangle) Area() float64 {
    w := r.BottomRight.X - r.TopLeft.X
    h := r.BottomRight.Y - r.TopLeft.Y
    return w * h
}

func main() {
    p1 := Point{0, 0}
    p2 := Point{3, 4}
    fmt.Printf("Distance: %.2f
", p1.Distance(p2))

rect := Rectangle{
        TopLeft:     Point{0, 0},
        BottomRight: Point{10, 5},
    }
    fmt.Printf("Area before: %.2f
", rect.Area())
    rect.Scale(2)
    fmt.Printf("Area after scale(2): %.2f
", rect.Area())
}