Can you explain structs and interfaces in Go with examples?

Can you explain structs and interfaces in Go with examples?

Sure! In Go, a struct is a composite data type that groups together variables (fields) under a single name. For example:

type Person struct {
    Name string
    Age  int
}

An interface, on the other hand, is a type that specifies a contract by defining methods that a struct must implement. Here's an example:

type Greeter interface {
    Greet() string
}

func (p Person) Greet() string {
    return "Hello, my name is " + p.Name
}

Can you show me how to use these in a program?

Absolutely! Here's a simple program that uses the Person struct and Greeter interface:

package main

import "fmt"

type Person struct {
    Name string
    Age  int
}

type Greeter interface {
    Greet() string
}

func (p Person) Greet() string {
    return "Hello, my name is " + p.Name
}

func main() {
    p := Person{Name: "Alice", Age: 30}
    fmt.Println(p.Greet())
}

What happens if a struct doesn't implement all methods of an interface?

If a struct does not implement all the methods of an interface, it will not satisfy that interface. This means you cannot assign an instance of that struct to a variable of the interface type. The Go compiler will raise an error if you try to do so.

Can you give me more examples of interfaces in Go?

Sure! Another common example is the Stringer interface, which requires a String() method. Here's how you can implement it:

type Book struct {
    Title  string
    Author string
}

func (b Book) String() string {
    return b.Title + " by " + b.Author
}

func main() {
    b := Book{Title: "1984", Author: "George Orwell"}
    fmt.Println(b.String())
}