Should golang files be closed?

The golang file needs to be closed. When operating a file in Golang, you need to open the file first. After the file opening operation is completed, you also need to close the file; because if you only open the file and do not close the file, it will cause a waste of system resources. In the Go language, the Close function is used to close a file. The syntax is "func (file *File) Close() error". The parameter "file" represents the open file; if the opening fails, an error message is returned, otherwise nil is returned.

The operating environment of this tutorial: Windows 7 system, GO version 1.18, Dell G3 computer.

Golang opens and closes files

When we operate a file in Golang, we need to open the file first. After the file opening operation is completed, we also need to close the file. If we only open the file , not closing the file will cause a waste of system resources.

To open a file in Golang, use the Open function, and to close a file, use the Close function. Opening a file, closing a file, and most file operations involve a very important structure, the os.File structure.

1.1 os.File structure

type File struct {
	*file // os specific
}
type file struct {
	pfd        poll.FD
	name       string
	dirinfo    *dirInfo // nil unless directory being read
	appendMode bool     // whether file is opened for appending
}

Description:
Here you can see the os.File structure The body contains a file pointer. The file pointer structure has four members, which are:

• pfd: It is an FD structure type and the only identifier of a file. Each one is opened. In the operating system, a file will have a file identifier to uniquely identify a file, which is pfd.
• name here: file name
• dirinfo: the path information of the file, which is also a structure Body
• appendMode: is a bool type, indicating whether the file can be appended to the content

1.2 Open function

Syntax:

func Open(name string) (*File, error)

Parameters:

• name: file name

Return value:

• File: The opened file handle
• err: If the opening fails, an error message is returned, otherwise nil is returned

Explanation

The Open function accepts a string file name as a parameter. If the opening is successful, it returns a pointer to the File structure, otherwise it returns an error message.

1.3 Close function

Syntax:

func (file *File) Close() error

Parameters:

• file: Open file

Return value

• error : If the opening fails, return an error message, otherwise return nil

Description:

• Use the File pointer to call the Close function. If the closing fails, The error message is returned.

1.4 Example description

Use the Open function to open the file and the Close function to close the file:

package main

import (
	"fmt"
	"os"
)

func main() {
	fmt.Println("Open File Test")
	fileName := "D:/go项目/test.go"
	file, err := os.Open(fileName)
	if err != nil {
		fmt.Println("Open file err:", err)
		return
	}
	fmt.Println("Open File Sucess")
	if err := file.Close(); err != nil {
		fmt.Println("Close File Err:", err)
		return
	}
	fmt.Println("Close File Success")
}

[Related recommendations: Go video tutorial, Programming teaching】

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