目錄
結構體
Golang 中,結構體是由一系列具有相同類型或不同類型的數據構成的數據集合。
結構體的定義使用了 type 和 struct 關鍵字。
- struct 關鍵字:定義一個新的數據類型,結構體中有一個或多個成員。
- type 關鍵字:設定了結構體的名稱。
結構體的格式如下:
type struct_variable_type struct {
member definition
member definition
...
member definition
}
一旦定義了結構體類型,它就能用於變量的聲明,與聲明基礎數據類型的變量無異。
格式:
variable_name := structure_variable_type {value1, value2...valuen}
// or
variable_name := structure_variable_type { key1: value1, key2: value2..., keyn: valuen}
示例:
package main
import "fmt"
type Books struct {
title string
author string
subject string
book_id int
}
func main() {
// 創建一個新的結構體
fmt.Println(Books{"Go 語言", "www.runoob.com", "Go 語言教程", 6495407})
// 也可以使用 key => value 格式
fmt.Println(Books{title: "Go 語言", author: "www.runoob.com", subject: "Go 語言教程", book_id: 6495407})
// 忽略初始化的成員爲 0 或 nil
fmt.Println(Books{title: "Go 語言", author: "www.runoob.com"})
}
訪問結構體成員
使用 .
成員訪問符,來訪問結構體的成員。
package main
import "fmt"
type Books struct {
title string
author string
subject string
book_id int
}
func main() {
var Book1 Books /* 聲明 Book1 爲 Books 類型 */
var Book2 Books /* 聲明 Book2 爲 Books 類型 */
/* book 1 描述 */
Book1.title = "Go 語言"
Book1.author = "www.runoob.com"
Book1.subject = "Go 語言教程"
Book1.book_id = 6495407
/* book 2 描述 */
Book2.title = "Python 教程"
Book2.author = "www.runoob.com"
Book2.subject = "Python 語言教程"
Book2.book_id = 6495700
/* 打印 Book1 信息 */
fmt.Printf( "Book 1 title : %s\n", Book1.title)
fmt.Printf( "Book 1 author : %s\n", Book1.author)
fmt.Printf( "Book 1 subject : %s\n", Book1.subject)
fmt.Printf( "Book 1 book_id : %d\n", Book1.book_id)
/* 打印 Book2 信息 */
fmt.Printf( "Book 2 title : %s\n", Book2.title)
fmt.Printf( "Book 2 author : %s\n", Book2.author)
fmt.Printf( "Book 2 subject : %s\n", Book2.subject)
fmt.Printf( "Book 2 book_id : %d\n", Book2.book_id)
}
向函數傳遞結構體
你可以像其他數據類型一樣將結構體類型變量作爲參數傳遞給函數,結構體是作爲實參時採用的是值傳遞。
package main
import "fmt"
type Books struct {
title string
author string
subject string
book_id int
}
func main() {
var Book1 Books /* 聲明 Book1 爲 Books 類型 */
var Book2 Books /* 聲明 Book2 爲 Books 類型 */
/* book 1 描述 */
Book1.title = "Go 語言"
Book1.author = "www.runoob.com"
Book1.subject = "Go 語言教程"
Book1.book_id = 6495407
/* book 2 描述 */
Book2.title = "Python 教程"
Book2.author = "www.runoob.com"
Book2.subject = "Python 語言教程"
Book2.book_id = 6495700
/* 打印 Book1 信息 */
printBook(Book1)
/* 打印 Book2 信息 */
printBook(Book2)
}
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)
}
結構體指針
相對的,將結構體指針作爲函數實參傳入時,肯定是引用語義的。
聲明結構體指針類型變量:
var struct_pointer *Books
struct_pointer = &Book1
Golang 中訪問結構體指針類型變量的成員依然是使用成員訪問符 .
,而不像 C 語言那樣會有特殊的地址訪問符 ->
。
struct_pointer.title
示例:
package main
import "fmt"
type Books struct {
title string
author string
subject string
book_id int
}
func main() {
var Book1 Books /* Declare Book1 of type Book */
var Book2 Books /* Declare Book2 of type Book */
/* book 1 描述 */
Book1.title = "Go 語言"
Book1.author = "www.runoob.com"
Book1.subject = "Go 語言教程"
Book1.book_id = 6495407
/* book 2 描述 */
Book2.title = "Python 教程"
Book2.author = "www.runoob.com"
Book2.subject = "Python 語言教程"
Book2.book_id = 6495700
/* 打印 Book1 信息 */
printBook(&Book1)
/* 打印 Book2 信息 */
printBook(&Book2)
}
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)
}