Anonymous structures and fields in Golang

In Golang , structures (or structs) allow us to group elements of different types into a single unit, which is useful for modeling real-world entities. Anonymous structures in Golang are temporary structures without names that are used for one-time purposes, while anonymous fields allow embedding unnamed fields.

For example:

package main
import "fmt"

// struct học sinh với cấu trúc và trường ẩn danh
type Student struct {
    struct {    // Cấu trúc bên trong ẩn danh cho thông tin cá nhân
        name string
        enrollment int
    }
    GPA float64  // Trường chuẩn
}

func main() {
    student := Student{
        struct {
            name string
            enrollment int
        }{
            name: "A",
            enrollment: 12345,
        },
        GPA: 3.8,
    }
    fmt.Println("Name:", student.name)
    fmt.Println("Enrollment:", student.enrollment)
    fmt.Println("GPA:", student.GPA)
}

Syntax:

variable := struct {
    field1 dataType1
    field2 dataType2                                                          # Cấu trúc ẩn danh
    // Trường bổ sung khi cần
}{value1, value2}


type StructName struct {
    dataType1
    dataType2                                                                    # Trường ẩn danh                                        
    // Trường ẩn danh bổ sung
}

Anonymous Structures in Go

Anonymous structures in Go are defined without a name and are useful for creating temporary, disposable structures. Here is the syntax and code example.

Syntax:

variable := struct {
    field1 dataType1
    field2 dataType2
    // Các trường bổ sung khi cần
}{value1, value2}

For example:

package main
import "fmt"
// Cấu trúc sinh viên với cấu trúc bên trong ẩn danh cho thông tin cá nhân
type Student struct {
    personalDetails struct { // Cấu trúc ẩn danh bên trong cho thông tin cá nhân
        name       string
        enrollment int
    }
    GPA float64 // Trường chuẩn
}
func main() {
    // Khởi tạo cấu trúc bên trong cho student
    student := Student{
        personalDetails: struct {
            name       string
            enrollment int
        }{
            name:       "A",
            enrollment: 12345,
        },
        GPA: 3.8,
    }
    // Hiện giá trị
    fmt.Println("Name:", student.personalDetails.name)
    fmt.Println("Enrollment:", student.personalDetails.enrollment)
    fmt.Println("GPA:", student.GPA)
}

Result:

Name: A
Enrollment: 12345
GPA: 3.8

This code defines a Student structure with an anonymous personalDetails structure inside, storing the name and registration information. It then initializes student with values ​​for these fields and prints them out.

Anonymous fields

Anonymous fields in Go allow you to define fields without explicit names, only their types. This is useful when fields naturally follow the type name.

Syntax

type StructName struct {
    dataType1
    dataType2
    // Additional anonymous fields
}

For example:

package main
import "fmt"

// Cấu trúc học sinh bằng các trường ẩn danh
type Student struct {
    int     // Số đăng ký (trường ẩn danh)
    string  // Tên trường ẩn danh
    float64 // GPA (trường ẩn danh)
}

func main() {
    // Khởi tạo struct học sinh với các trường ẩn danh
    student := Student{12345, "A", 3.8}

    // Hiện giá trị
    fmt.Println("Enrollment:", student.int)
    fmt.Println("Name:", student.string)
    fmt.Println("GPA:", student.float64)
}

Result:

Enrollment: 12345
Name: A
GPA: 3.8

Here, the data types ( int, string, float64 ) act as field names, so accessing the values ​​depends on the types.

Important Points to Remember About Anonymous Fields in Golang

1. Unique requirement: You cannot use two fields of the same type in a structure. For example:

type InvalidStudent struct {
    int
    int // Error: duplicate type
}

2. Combining named and anonymous fields: You can combine anonymous and named fields in a structure.

type Student struct {
    id int // Named field
    int    // Anonymous field
}