结构体

定义结构体

结构体定义需要使用type和struct语句。struct语句定义了一个新的数据类型，结构体中有一个或多个成员。type语句设定了结构体的名称。结构体的格式如下

type struct_variable_type struct {
    member definition
    member definition
    ...
    member definition
}

一旦定义了结构体类型，它就能用于变量的声明，语法格式如下：

variable_name := structure_variable_type {val1,val2...valn}
variable_name := structure_variable_type {key1: val1, key2: val2 ... keyn: valuen}

package main
import "fmt"
type Books struct {
    title string
    author string
    subject string
    book_id int
}
func main() {
    b1 := Books{"Golang", "runoob", "Go", 1111}
    b2 := Books{title: "Golang", author: "runoob", subject: "Go", 2222}
    b3 := Books{title: "Golang"}
}

访问结构体

使用.操作符

package main
import "fmt"
type Books struct {
    title string
    author string
    subject string
    book_id int
}
func main() {
    var book1 Books
    book1.title = "Golang"
    book1.author = "Google"
    book1.subject = "Go"
    book1.book_id = 1111
    fmt.Println(book1.title)
}

结构体作为函数参数

package main
import "fmt"
type Books struct {
   title string
   author string
   subject string
   book_id int
}
func main() {
       var Book1 Books
       Book1.title = "Go 语言"
       Book1.author = "www.runoob.com"
       Book1.subject = "Go 语言教程"
       Book1.book_id = 6495407
       printBook(Book1)
}
func printBook(book Books) {
   fmt.Printf( "Book title : %s\n", book.title)
   fmt.Printf( "Book author : %s\n", book.author)
   fmt.Printf( "Book subject : %s\n", book.subject)
   fmt.Printf( "Book book_id : %d\n", book.book_id)
}

结构体指针

定义指向结构体的指针类似于其他指针变量，格式如下、

var struct_pointer *Books

以上定义的指针变量可以存储结构体变量的地址。查看结构体变量地址，可以将&符号放置于结构体变量前：

struct_pointer = &Book1

使用结构体指针访问结构体成员，使用.符号

struct_pointer.title

传结构体地址，函数的形参为指针类型

func printBook( book *Books ) {
   fmt.Printf( "Book title : %s\n", book.title)
   fmt.Printf( "Book author : %s\n", book.author)
   fmt.Printf( "Book subject : %s\n", book.subject)
   fmt.Printf( "Book book_id : %d\n", book.book_id)
}