在其他語言中，這類似於公共存取限定符。
如果結構體的欄位（即屬性）以大寫開頭，則表示該欄位已匯出，因此可以在套件外部存取。
假設Go專案中有以下檔案：
main.go /library /book.go
我們將在它自己的套件中定義 book.go。
// library/book.go
// Assume we have a package called "library" which contains a book.
package library
// Struct that represents a physical book in a library with exported fields
type Book struct {
Title string,
Author string
}
在main.go使用時：
package main
import (
"fmt"
"library" // importing the package that the struct Book is in
)
func main() {
book := library.Book{
Title: "Book Title",
Author: "John Snow"
}
// Print the title and author to show that the struct Book fields are accessible outisde it's package "library"
fmt.Println("Title:", book.Title)
fmt.Println("Author:", book.Author)
}
在 Ruby 中，這與使用 attr_accessor 是同義的，因為我們可以：
class Book
# allow read and write on the attributes from outside the class
attr_accessor(:title, :author)
def initalize(title = nil, author = nil)
@title = title
@author = authoer
end
end
# usage outside of the class
book = Book.new()
# assinging attributes outside of the class
book.title = "Book Title"
book.title = "Jon Snow"
# accessing attributes outside of the class
puts book.title, book.author
這類似於其他語言中的私有存取限定符
如果以小寫開頭，則這些欄位將無法存取。
親自嘗試！
假設你的模組名稱是 go.mod 中的 myapp
// go.mod module myapp go 1.22.5
我們在套件library下的library/book.go中建立一個新檔案
// library/book.go
// Assume we have a package called "library" which contains a book.
package library
// Fields start with lowercase, fields are not exported
type Book struct {
title string
author string
}
將套件導入main.go
// main.go
package main
import (
"fmt"
// import the library package
"myapp/library"
)
func main() {
book := library.Book{
title: "Book Title",
author: "John Snow"
}
// Print the title and author to show that the struct Book fields are accessible outisde it's package "library"
fmt.Println("title:", book.title)
fmt.Println("author:", book.author)
}
如果您在 VSCode 中設定了 Go，您會收到以下 lint 錯誤：
unknown field author in struct literal of type library.Bookcompiler[MissingLitField](https://pkg.go.dev/golang.org/x/tools/internal/typesinternal#MissingLitField
以上是Golang 結構字段範圍的詳細內容。更多資訊請關注PHP中文網其他相關文章！
