The structure is a data collection composed of a series of data of the same type or different types.
Arrays in Go language can store the same type of data, but in the structure we can define different data types for different items.
Structure definition
Structure definitions need to use type and struct statements.
The struct statement defines a new data type with one or more members in the structure.
The type statement sets the name of the structure.
The format of the structure is as follows:
type test struct {
member definition
member definition
...
member definition
}Once the structure type is defined, it can be used for variable declarations. The syntax format is as follows:
variable_name := test {
value1, value2...valuen}
或
variable_name := test {
key1: value1, key2: value2..., keyn: valuen}Example:
package main
import "fmt"
type Books struct {
title string
author string
subject string
book_id int
}
func main() {
// 创建一个新的结构体
fmt.Println(Books{
"Go 语言", "zhangsan", "Go 语言教程", 34324})
// 也可以使用 key => value 格式
fmt.Println(Books{
title: "Go 语言", author: "zhangsan", subject: "Go 语言教程", book_id: 878756})
// 忽略的字段为 0 或 空
fmt.Println(Books{
title: "Go 语言", author: "zhangsan"})
}Access structure member
If you want to access the members of the structure, you need to use a dot. The operator
format is:
Structure. Member name
Structure type variables are defined using the struct keyword
package main
import "fmt"
type Books struct {
title string
author string
subject string
book_id int
}
func main() {
var Book1 Books /* 声明 Book1 为 Books 类型 */
var Book2 Books /* 声明 Book2 为 Books 类型 */
/* book 1 描述 */
Book1.title = "Go 语言"
Book1.author = "www.runoob.com"
Book1.subject = "Go 语言教程"
Book1.book_id = 6495407
/* book 2 描述 */
Book2.title = "Python 教程"
Book2.author = "www.runoob.com"
Book2.subject = "Python 语言教程"
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)
}This is very similar to calling in JAVA. After defining the object, encapsulating the member variable, you can use. To call the member variable.
But the go language only supports encapsulation, and does not support inheritance and polymorphism, which is different from JAVA.
The running result is:
Book 1 title : Go 语言
Book 1 author : www.runoob.com
Book 1 subject : Go 语言教程
Book 1 book_id : 6495407
Book 2 title : Python 教程
Book 2 author : www.runoob.com
Book 2 subject : Python 语言教程
Book 2 book_id : 6495700The structure type is passed to the function as a parameter
The pointer is not used to pass by value, and the source address can be changed by adding the pointer. Note that the pointer is used but the.
package main
import "fmt"
type Books struct {
title string
author string
subject string
book_id int
}
func main() {
var Book1 Books /* 声明 Book1 为 Books 类型 */
var Book2 Books /* 声明 Book2 为 Books 类型 */
/* book 1 描述 */
Book1.title = "Go 语言"
Book1.author = "www.runoob.com"
Book1.subject = "Go 语言教程"
Book1.book_id = 6495407
/* book 2 描述 */
Book2.title = "Python 教程"
Book2.author = "www.runoob.com"
Book2.subject = "Python 语言教程"
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)
}You can directly take a as the structure address, and such a is also compatible with ordinary type operations, so it is a common situation
code show as below:
package main
import "fmt"
type test struct{
Name string
Age int
}
func A(t* test){
t.Age = 15
}
func main(){
a:=&test{
Name:"john",
Age: 19,
}
A(a)
fmt.Println(a)
a.Age=20
fmt.Println(a)
}Structure pointer
Defining a pointer to a structure is similar to other pointer variables in the following format:
var struct_pointer *BooksThe pointer variable defined above can store the address of the structure variable. To view the address of the structure variable, the & symbol can be placed before the structure variable:
struct_pointer = &Book1Use structure pointers to access structure members, use the "." operator:
struct_pointer.titleUse the structure pointer to rewrite the above example, the code is as follows:
package main
import "fmt"
type Books struct {
title string
author string
subject string
book_id int
}
func main() {
var Book1 Books
var Book2 Books
/* book 1 描述 */
Book1.title = "Go 语言"
Book1.author = "www.runoob.com"
Book1.subject = "Go 语言教程"
Book1.book_id = 6495407
/* book 2 描述 */
Book2.title = "Python 教程"
Book2.author = "www.runoob.com"
Book2.subject = "Python 语言教程"
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)
}The running result is:
Book title : Go 语言
Book author : www.runoob.com
Book subject : Go 语言教程
Book book_id : 6495407
Book title : Python 教程
Book author : www.runoob.com
Book subject : Python 语言教程
Book book_id : 6495700Anonymous structure
package main
import "fmt"
func main(){
a:=struct{
Name string
Age int
}
{
Name:"joe",
Age:19,
}
fmt.Println(a)
}Structure nesting
package main
import "fmt"
type human struct{
Sex int
}
type teacher struct{
human
Name string
Age int
}
type student struct{
human
Name string
Age int
}
func main(){
a:=student{
Name:"joe",Age:19,human:human{
Sex:0}};
b:=teacher{
Name:"joe",Age:20,human:human{
Sex:0}};
fmt.Println(a,b)
a.Sex=1
fmt.Println(a,b)
}