Structs

Go’s structs are typed collections of fields. They’re useful for grouping data together to form records.

package main

import "fmt"

// This person struct type has name and age fields.
type person struct {
    name string
    age  int
}

// newPerson constructs a new person struct with the given name.
func newPerson(name string) *person {

    // You can safely return a pointer to local variable
    // as a local variable will survive the scope of the function.
    p := person{name: name}
    p.age = 42
    return &p
}

func main() {

    // This syntax creates a new struct.
    fmt.Println(person{"Bob", 20})

    // You can name the fields when initializing a struct.
    fmt.Println(person{name: "Alice", age: 30})

    // Omitted fields will be zero-valued.
    fmt.Println(person{name: "Fred"})

    // An & prefix yields a pointer to the struct.
    fmt.Println(&person{name: "Ann", age: 40})

    // It’s idiomatic to encapsulate new struct creation in constructor functions
    fmt.Println(newPerson("Jon"))

    // Access struct fields with a dot.
    s := person{name: "Sean", age: 50}
    fmt.Println(s.name)

    // You can also use dots with struct pointers -
    // the pointers are automatically dereferenced.
    sp := &s
    fmt.Println(sp.age)

    // Structs are mutable.
    sp.age = 51
    fmt.Println(sp.age)
}

$ go run structs.go
{Bob 20}
{Alice 30}
{Fred 0}
&{Ann 40}
&{Jon 42}
Sean
50
51