定義&實例化

定義方式:

type 類別名 struct {
    名稱1  類型
    Age   int
    Color Color //可定義別的結構體或自己
}

實例化方式:

var instance T
instance := new(T)
instance *T
instance := &T{}

package main

import "fmt"

//結構體
type User struct {
    Name  string
    Age   int
    Color Color //可定義別的結構體或自己
}

type Color struct {
    R, G, B string
}

func main() {


    var user User
    user.Age = 20
    user.Name = "bocky"
    user.Color.R = "red"
    print(user.Color.R, user.Age) // red20

    user := new(User)
    user.Age = 25
    user.Name = "Abby"

    user1 := &User{}
    user1.Name = "Car"
    user1.Age = 30


    //下方利用function來實例化
    user2 := NewUser("NAME1", 100)
    fmt.Println(user2.Name) //NAME1
    fmt.Println(user2.Age)  //100
}

func NewUser(name string, age int) *User {
    return &User{
        Name: name,
        Age:  age,
    }
}

初始化成員變量

package main

import "fmt"

type Person struct {
    name  string
    chile *Person
}

type User struct {
    Name   string
    Sex    int
    Email  string
    Mobile string
}

func main() {

    Person := &Person{name: "奶奶", chile: &Person{name: "媽媽", chile: &Person{name: "我"}}}

    fmt.Println(Person.chile.chile.name) // 我

    user1 := User{
        "Bocky",
        1,
        "a123456@gmail.com",
        "0123456789",
    }
    fmt.Println(user1) //{Bocky 1 shty@gmail.com 0123456789}

    //定義完後馬上初始化
    user2 := &struct { //1.定義
        id   int
        name string
    }{ //2.初始化
        22222333333,
        "Amy",
    }
    fmt.Println(user2) //&{22222333333 Amy}
}

Go中的方法與接收器 (必學)

將函數與結構體綁定
格式:

func (接收器變量 接收器類型) 函數名(參數列表) (返回参数){
        函數體
}

package main

import "fmt"


type User struct {
    Name string
    Age  int
}

func main() {
    user1 := &User{
        Name: "AAAA",
        Age:  30,
    }
    fmt.Println("===有指標的類型===")
    user1.PprintName() //Name: Bocky
    user1.PprintAge()  //Age: 30
    user1.PprintName() //Name: BBB

    fmt.Println("===沒有指標類型===")

    user2 := &User{
        Name: "AAAA",
        Age:  30,
    }
    user2.printName() //Name: AAAA
    user2.printAge()
    //Name: BBB
    //Age: 30
    user2.printName() //Name: AAAA
}

// 由此function調用, 可使用指針來修改值
func (user *User) PprintName() {
    fmt.Println("Name:", user.Name)
}

func (user *User) PprintAge() { // 使用*User 指針類型是可改值的
    user.Name = "BBB" // 原本是AAAA改成BBB
    fmt.Println("Age:", user.Age)
}

// 非指針類型的接收器
func (user User) printName() {
    fmt.Println("Name:", user.Name)
}
func (user User) printAge() { // 使用*User 指針類型是可改值的
    user.Name = "BBB"
    fmt.Println("Name:", user.Name) // 原本是AAAA改成BBB, Name: BBB
    fmt.Println("Age:", user.Age)   //Age: 30
}

印出結果:

===有指標的類型===
Name: AAAA
Age: 30
Name: BBB
===沒有指標類型===
Name: AAAA
Name: BBB
Age: 30
Name: AAAA