结构体是由一些列属性组成的复合数据类型，每个数据都具有名称，结构体将属性组合在一起进行由程序进行处理

1、自定义类型

在Go语言中使用type声明一种新的类型，语法格式：

type TypeName Formatter 

  1. package main
  3. import "fmt"
  5. // Counter 见类型知含义 & 可以添加方法
  6. // Counter 现有数据类型
  7. type Counter int
  9. type User map[string]string
  11. type Callback func() error
  13. func main() {
  14.     var counter Counter
  15.     fmt.Printf("%T,%v\n", counter, counter) // main.Counter,0
  16.     counter += 10
  17.     fmt.Printf("%T,%v\n", counter, counter) // main.Counter,10
  18.     s2 := Counter(20) + counter             //类型转换
  19.     fmt.Printf("%T,%v\n", s2, s2)           // main.Counter,30
  21.     var user User = make(User)
  22.     fmt.Printf("%T,%v\n", user, user) // main.User,map[]
  23.     user["id"] = "1"
  24.     fmt.Println(user) // map[id:1]
  26.     callback := map[string]Callback{}
  27.     callback["add"] = func() error {
  28.         fmt.Println("add")
  29.         return nil
  30.     }
  31.     callback["add"]() // add
  33. }

2、别名

  1. package main
  3. import (
  4.     "fmt"
  5. )
  7. type Counter = int // 别名
  9. func main() {
  10.     var counter Counter
  11.     fmt.Printf("%T,%v\n", counter, counter) // int,0
  12.     var num int = 10
  13.     fmt.Println(num + counter) // 10
  14. }

3、结构体

  1. package main
  3. import (
  4.     "fmt"
  5.     "time"
  6. )
  8. // User 定义结构体
  9. type User struct {
  10.     id       int
  11.     name     string
  12.     addr     string
  13.     tel      string
  14.     birthday time.Time
  15. }
  17. func main() {
  18.     var user User
  19.     // 零值是由个元素的零组成的一个结构体的变量
  20.     fmt.Printf("%T,%v\n", user, user) // main.User,{0    {0 0 <nil>}}
  22.     // 字面量(按照属性顺序定义的字面量)
  23.     // 必须严格按照结构体属性定义顺序
  24.     // 每个属性都必须指定
  25.     user = User{10, "dadong", "北京", "123456789", time.Now()}
  26.     fmt.Printf("%#v\n", user) // main.User{id:10, name:"dadong", addr:"北京", tel:"123456789", birthday:time.Time{wall:0xc038093d10d8df50, ext:4793801, loc:(*time.Location)(0x1eb560)}}
  28.     //按照属性名定义的字面量
  29.     user = User{id: 20, name: "xxd"}
  30.     fmt.Printf("%#v\n", user) // main.User{id:20, name:"xxd", addr:"", tel:"", birthday:time.Time{wall:0x0, ext:0, loc:(*time.Location)(nil)}}
  32.     // 属性访问和修改
  33.     fmt.Println(user.id)
  34.     user.id = 100
  35.     user.name = "xisuo"
  36.     fmt.Printf("%#v\n", user) // main.User{id:100, name:"xisuo", addr:"", tel:"", birthday:time.Time{wall:0x0, ext:0, loc:(*time.Location)(nil)}}
  37. }

4、结构体指针类型

  1. package main
  3. import (
  4.     "fmt"
  5.     "time"
  6. )
  8. // User 定义结构体
  9. type User struct {
  10.     id       int
  11.     name     string
  12.     addr     string
  13.     tel      string
  14.     birthday time.Time
  15. }
  17. func main() {
  18.     var user = &User{name: "dadong", id: 10}
  19.     fmt.Printf("%T,%#v\n", user, user) // *main.User,&main.User{id:10, name:"dadong", addr:"", tel:"", birthday:time.Time{wall:0x0, ext:0, loc:(*time.Location)(nil)}}
  21.     // new函数初始化
  22.     // 初始化结构体指针
  23.     user = new(User)
  24.     fmt.Printf("%T,%#v\n", user, user) // *main.User,&main.User{id:0, name:"", addr:"", tel:"", birthday:time.Time{wall:0x0, ext:0, loc:(*time.Location)(nil)}}
  26.     u2 := new(User)
  27.     fmt.Printf("%T,%#v\n", u2, u2) // *main.User,&main.User{id:0, name:"", addr:"", tel:"", birthday:time.Time{wall:0x0, ext:0, loc:(*time.Location)(nil)}}
  28. }

5、匿名结构体

  1. package main
  3. import (
  4.     "fmt"
  5.     "time"
  6. )
  8. func main() {
  9.     // 匿名结构体
  10.     var user struct {
  11.         id       int
  12.         name     string
  13.         tel      string
  14.         addr     string
  15.         birthday time.Time
  16.     }
  17.     fmt.Printf("%T,\n%#v\n", user, user)
  18.     //struct { id int; name string; tel string; addr string; birthday time.Time },
  19.     //struct { id int; name string; tel string; addr string; birthday time.Time }{id:0, name:"", tel:"", addr:"", birthday:time.Time{wall:0x0, ext:0, loc:(*time.Location)(nil)}}
  21.     user = struct {
  22.         id       int
  23.         name     string
  24.         tel      string
  25.         addr     string
  26.         birthday time.Time
  27.     }{10, "dadong", "13500000", "xxxxxxx", time.Now()} // 结构体类型
  28.     fmt.Printf("%T,\n%#v\n", user, user)
  29.     //struct { id int; name string; tel string; addr string; birthday time.Time },
  30.     //struct { id int; name string; tel string; addr string; birthday time.Time }{id:10, name:"dadong", tel:"13500000", addr:"xxxxxxx", birthday:time.Time{wall:0xc0380e4e4475cc00, ext:4365301, loc:(*time.Location)(0xb3b560)}}
  32.     user = struct {
  33.         id       int
  34.         name     string
  35.         tel      string
  36.         addr     string
  37.         birthday time.Time
  38.     }{name: "dadong", id: 10} // 结构体类型
  39.     fmt.Printf("%T,\n%#v\n", user, user)
  40.     //struct { id int; name string; tel string; addr string; birthday time.Time },
  41.     //struct { id int; name string; tel string; addr string; birthday time.Time }{id:10, name:"dadong", tel:"", addr:"", birthday:time.Time{wall:0x0, ext:0, loc:(*time.Location)(nil)}}
  43.     var u2 = struct {
  44.         id   int
  45.         name string
  46.     }{id: 10, name: "dadong"}
  47.     fmt.Printf("%T,\n%#v\n", u2, u2)
  48.     //struct { id int; name string },
  49.     //struct { id int; name string }{id:10, name:"dadong"}
  51. }

5.1 多层及使用

  1. package main
  3. import (
  4.     "fmt"
  5.     "time"
  6. )
  8. type Addr struct {
  9.     province string
  10.     street   string
  11.     numbe    string
  12. }
  14. type Tel struct {
  15.     prefix string
  16.     number string
  17. }
  19. // User 组合
  20. type User struct {
  21.     id       int
  22.     name     string
  23.     tel      Tel
  24.     addr     Addr
  25.     birthday time.Time
  26. }
  28. func main() {
  29.     var user User = User{
  30.         id:   0,
  31.         name: "",
  32.         tel: Tel{
  33.             prefix: "",
  34.             number: "",
  35.         },
  36.         addr: Addr{
  37.             province: "北京市",
  38.             street:   "",
  39.             numbe:    "",
  40.         },
  41.         birthday: time.Now(),
  42.     }
  43.     fmt.Println(user.addr.province) // 北京市
  44. }