Go language structure
Go arrays in the language can store the same type of data, but in structures we can define different data types for different items.
A structure is a collection of data that consists of a series of data of thesame type or different types.
A structure represents a record, such as keeping a record of a book in a library, and each book has the following attributes:
Title
Author
Subject
ID
Define the structure
The structure definition needs to use the type and struct statement. struct statement defines a new data type with one or more members in the structure. type statement sets the name of the structure. The format of the structure is as follows:
type struct_variable_type struct {
member definition
member definition
...
member definition
}
Once the structure type is defined, it can be used for variable declaration,and the syntax format is as follows:
variable_name := structure_variable_type {value1, value2...valuen}
or
variable_name := structure_variable_type { key1: value1, key2: value2..., keyn: valuen}
Examples are as follows:
Example
package main
import "fmt"
type Books struct {
title string
author string
subject string
book_id int
}
func main() {
// Create a new structure
fmt.Println(Books{"Go language", "www.runoob.com", "Go Language Tutorial",
6495407})
// You can also use the key=>value format
fmt.Println(Books{title: "Go language", author: "www.runoob.com",
subject: "Go Language Tutorial", book_id: 6495407})
// Ignored field is 0 or empty
fmt.Println(Books{title: "Go language", author: "www.runoob.com"})
}
The output is as follows:
{Go Language www.runoob.com Go Language Tutorial 6495407}
{Go Language www.runoob.com Go Language Tutorial 6495407}
{Go Language www.runoob.com 0}
Access structure members
If you want to access structure members, you need to use a period . operator in the format:
Structure.Member name“
Structure type variables use the struct keyword definition. An example is as follows:
Example
package main
import "fmt"
type Books struct {
title string
author string
subject string
book_id int
}
func main() {
var Book1 Books /* Declare Book1 as a Book type */
var Book2 Books /* Declare Book2 as a Book type */
/* book 1 describe */
Book1.title = "Go Language"
Book1.author = "www.runoob.com"
Book1.subject = "Go Language Tutorial"
Book1.book_id = 6495407
/* book 2 describe */
Book2.title = "Python Tutorial"
Book2.author = "www.runoob.com"
Book2.subject = "Python Language Tutorial"
Book2.book_id = 6495700
/* Print Book1 information */
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)
/* Print Book2 information */
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)
}
The execution result of the above example is:
Book 1 title : Go Language
Book 1 author : www.runoob.com
Book 1 subject : Go Language Tutorial
Book 1 book_id : 6495407
Book 2 title : Python Tutorial
Book 2 author : www.runoob.com
Book 2 subject : Python Language Tutorial
Book 2 book_id : 6495700
Structure as a function parameter
You can pass the structure type as an argument to the function like any other data type. And access the structure variables as shown in the above example:
Example
package main
import "fmt"
type Books struct {
title string
author string
subject string
book_id int
}
func main() {
var Book1 Books /* Declare Book1 as a Book type */
var Book2 Books /* Declare Book2 as a Book type */
/* book 1 describe */
Book1.title = "Go language"
Book1.author = "www.runoob.com"
Book1.subject = "Go Language Tutorial"
Book1.book_id = 6495407
/* book 2 describe */
Book2.title = "Python Tutorial"
Book2.author = "www.runoob.com"
Book2.subject = "Python Language Tutorial"
Book2.book_id = 6495700
/* Print Book1 information */
printBook(Book1)
/* Print Book2 information */
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 execution result of the above example is:
Book title : Go Language
Book author : www.runoob.com
Book subject : Go Language Tutorial
Book book_id : 6495407
Book title : Python Tutorial
Book author : www.runoob.com
Book subject : Python Language Tutorial
Book book_id : 6495700
Structure pointer
You can define pointers to structures that are similar to other pointer variables in the following format:
var struct_pointer *Books
The pointer variable defined above can store the address of the structure variable. To view the address of the structure variable, you can set the & symbol is placed in front of the structural variable:
struct_pointer = &Book1
Use structure pointers to access structure members, using the "." operator:
struct_pointer.title
Next, let’s rewrite the above example with a structure pointer, as follows:
Example
package main
import "fmt"
type Books struct {
title string
author string
subject string
book_id int
}
func main() {
var Book1 Books /* Declare Book1 as a Book type */
var Book2 Books /* Declare Book2 as a Book type */
/* book 1 describe */
Book1.title = "Go language"
Book1.author = "www.runoob.com"
Book1.subject = "Go Language Tutorials"
Book1.book_id = 6495407
/* book 2 describe */
Book2.title = "Python Tutorials"
Book2.author = "www.runoob.com"
Book2.subject = "Python Language Tutorials"
Book2.book_id = 6495700
/* Print Book1 information */
printBook(&Book1)
/* Print Book2 information */
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 execution result of the above example is:
Book title : Go Language
Book author : www.runoob.com
Book subject : Go Language Tutorial
Book book_id : 6495407
Book title : Python Tutorial
Book author : www.runoob.com
Book subject : Python Language Tutorial
Book book_id : 6495700