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Structs in Go

Structs in Go are user-defined types that group together fields. They are similar to classes in other languages but do not support inheritance. Structs are widely used in Go for organizing and managing data.

Defining a Struct

A struct is defined using the type and struct keywords. Structs can contain fields of different types. 


package main

import "fmt"

type Person struct {
    Name string
    Age  int
}

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

Methods on Structs

Methods are functions that operate on a specific type. They are defined with a receiver argument, which can be a value or a pointer. 


package main

import "fmt"

type Person struct {
    Name string
    Age  int
}

// Method with a value receiver
func (p Person) Greet() {
    fmt.Println("Hello, my name is", p.Name)
}

// Method with a pointer receiver
func (p *Person) Birthday() {
    p.Age++
}

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

Embedded Structs

Structs can be embedded within other structs to create more complex data structures. This is similar to inheritance in other languages. 


package main

import "fmt"

type Address struct {
    City  string
    State string
}

type Person struct {
    Name    string
    Age     int
    Address Address
}

func main() {
    p := Person{
        Name: "Alice",
        Age:  25,
        Address: Address{
            City:  "New York",
            State: "NY",
        },
    }
    fmt.Println("Name:", p.Name)
    fmt.Println("City:", p.Address.City)
}

Pointers to Structs

You can use pointers to structs to avoid copying large structs and to modify the original struct. 


package main

import "fmt"

type Person struct {
    Name string
    Age  int
}

func (p *Person) UpdateName(newName string) {
    p.Name = newName
}

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

Anonymous Structs

Anonymous structs are structs that are defined without a name. They are useful for one-time use cases. 


package main

import "fmt"

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

Struct Tags

Struct tags are used to attach metadata to struct fields. They are commonly used in JSON encoding/decoding. 


package main

import (
    "encoding/json"
    "fmt"
)

type Person struct {
    Name string `json:"name"`
    Age  int    `json:"age"`
}

func main() {
    p := Person{Name: "Alice", Age: 25}
    jsonData, _ := json.Marshal(p)
    fmt.Println("JSON:", string(jsonData))
}

Practical Use Cases

Structs are widely used in Go for:

Next: Interfaces in Go