Go Programming Language Methods

Introduction

This lab aims to test the knowledge of the Go programming language's method feature.

Skills Graph

Methods

The code provided defines a struct type called rect with two fields, width and height. Two methods are defined for this struct type, area and perim. The area method calculates the area of the rectangle, and the perim method calculates the perimeter of the rectangle. The main function calls these two methods and prints their results.

• The area method should have a receiver type of *rect.
• The perim method should have a receiver type of rect.
• The area method should return the area of the rectangle.
• The perim method should return the perimeter of the rectangle.
• The main function should call both methods and print their results.

$ go run methods.go
area: 50
perim: 30
area: 50
perim: 30

## Next we'll look at Go's mechanism for grouping and
## naming related sets of methods: interfaces.

There is the full code below:

// Go supports _methods_ defined on struct types.

package main

import "fmt"

type rect struct {
	width, height int
}

// This `area` method has a _receiver type_ of `*rect`.
func (r *rect) area() int {
	return r.width * r.height
}

// Methods can be defined for either pointer or value
// receiver types. Here's an example of a value receiver.
func (r rect) perim() int {
	return 2*r.width + 2*r.height
}

func main() {
	r := rect{width: 10, height: 5}

	// Here we call the 2 methods defined for our struct.
	fmt.Println("area: ", r.area())
	fmt.Println("perim:", r.perim())

	// Go automatically handles conversion between values
	// and pointers for method calls. You may want to use
	// a pointer receiver type to avoid copying on method
	// calls or to allow the method to mutate the
	// receiving struct.
	rp := &r
	fmt.Println("area: ", rp.area())
	fmt.Println("perim:", rp.perim())
}

Summary

This lab tests the ability to define methods in Go and use them to perform calculations on struct types. The area and perim methods are defined for the rect struct type, and the main function calls these methods and prints their results.