Section 4 of 12

Structs & Interfaces

Object-oriented programming in Go with structs and interfaces

Course Progress

Section 4 of 12

33% complete

Tutorials

Structs

Structs are collections of fields, Go's way of grouping data together.

Code Examples

Struct Definitiongo
package main

import "fmt"

// Define a struct
type Person struct {
    Name  string
    Age   int
    Email string
}

// Method on struct
func (p Person) Greet() {
    fmt.Printf("Hello, I'm %s\n", p.Name)
}

// Pointer receiver - can modify the struct
func (p *Person) HaveBirthday() {
    p.Age++
}

func main() {
    // Create struct instance
    person := Person{
        Name:  "Alice",
        Age:   25,
        Email: "alice@example.com",
    }
    
    fmt.Println(person)
    person.Greet()
    
    person.HaveBirthday()
    fmt.Println(person.Age)
}

Interfaces

Interfaces define a set of methods that a type must implement. This enables polymorphism in Go.

Code Examples

Interface Implementationgo
package main

import "fmt"

// Define an interface
type Writer interface {
    Write(data string) error
}

type FileWriter struct {
    filename string
}

func (fw FileWriter) Write(data string) error {
    fmt.Printf("Writing to file %s: %s\n", fw.filename, data)
    return nil
}

type ConsoleWriter struct{}

func (cw ConsoleWriter) Write(data string) error {
    fmt.Println("Console:", data)
    return nil
}

func SaveData(w Writer, data string) {
    w.Write(data)
}

func main() {
    fw := FileWriter{filename: "output.txt"}
    cw := ConsoleWriter{}
    
    SaveData(fw, "Hello")
    SaveData(cw, "World")
}

Exercises

Shape Calculator

Create structs for Rectangle and Circle with an Area method

INTERMEDIATE

Starter Code:

package main

import (
    "fmt"
    "math"
)

type Rectangle struct {
    Width  float64
    Height float64
}

type Circle struct {
    Radius float64
}

// TODO: Implement Area method for Rectangle
// TODO: Implement Area method for Circle

func main() {
    rect := Rectangle{Width: 5, Height: 4}
    circle := Circle{Radius: 3}
    
    fmt.Println("Rectangle area:", rect.Area())
    fmt.Println("Circle area:", circle.Area())
}

Hands-on Project

Employee Management System

Create an employee management system with different employee types

ADVANCED

Learning Objectives

  • >Design structs
  • >Implement interfaces
  • >Use polymorphism

Project Tips

  • > Start by understanding the requirements
  • > Break the project into smaller tasks
  • > Test your code frequently as you build
  • > Add error handling throughout your code
  • > Consider edge cases and validate inputs
  • > Document your code with comments
Arrays, Slices & MapsHOMEError Handling