Introduction to Structs

Structs in Go allow you to define complex data types by grouping variables of different types together. They are useful for representing real-world entities.

Defining and Using a Struct

Structs are defined using the type keyword followed by the struct name and fields.

package main

import "fmt"

type Person struct {
    Name string
    Age  int
}

func main() {
    p := Person{Name: "Alice", Age: 25}
    fmt.Println(p)
}

This example defines a Person struct and initializes it with values.

Accessing and Modifying Struct Fields

Fields of a struct can be accessed and modified using dot notation.

package main

import "fmt"

type Person struct {
    Name string
    Age  int
}

func main() {
    p := Person{Name: "Alice", Age: 25}
    fmt.Println("Before update:", p.Name, p.Age)
    p.Age = 30  // Updating the Age field
    fmt.Println("After update:", p.Name, p.Age)
}

Here, we update Alice’s age from 25 to 30.

Structs with Methods

Structs in Go can have methods, which are functions with a receiver.

package main

import "fmt"

type Person struct {
    Name string
    Age  int
}

func (p Person) Greet() {
    fmt.Println("Hello, my name is", p.Name)
}

func main() {
    p := Person{Name: "Alice", Age: 25}
    p.Greet()
}

This example adds a Greet method to the Person struct.

Pointers to Structs

Structs can be used with pointers to modify values directly.

package main

import "fmt"

type Person struct {
    Name string
    Age  int
}

func (p *Person) IncreaseAge() {
    p.Age++
}

func main() {
    p := Person{Name: "Alice", Age: 25}
    p.IncreaseAge()
    fmt.Println("New Age:", p.Age)
}

Using a pointer receiver allows modifying the struct fields directly.

Anonymous Structs

Go also allows creating anonymous structs without defining a type.

package main

import "fmt"

func main() {
    person := struct {
        Name string
        Age  int
    }{Name: "Alice", Age: 25}

    fmt.Println(person)
}

This example defines and initializes an anonymous struct in a single step.

Conclusion

Structs in Go are powerful and allow defining custom data types. They enable object-oriented programming features such as encapsulation, methods, and pointers.

In the next lesson, we will explore Interfaces in Go, which provide a way to define behavior without specifying exact data types.