What are the methods for reading files in golang?

Golang's method of reading files: 1. Use the os package and the os.Open function; 2. Use the bufio package and the Scanner type; 3. Use the ioutil package and the ReadFile function; 4. Use the os/exec package and A combination of command line tools to read file contents. Detailed introduction: 1. Use the os package and the os.Open function. This is one of the most basic methods. You open the file by using the "os.Open" function and return a file object of type "*os.File" and so on.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

In the Go language, there are many ways to read files. The following are several common methods:

1. Use the os package and the os.Open function

This is one of the most basic methods, by using os.Open The function opens a file and returns a file object of type *os.File. You can then use the file object's methods to read the file contents.

package main  
  
import (  
 "fmt"  
 "os"  
)  
  
func main() {  
 file, err := os.Open("file.txt")  
 if err != nil {  
 fmt.Println("无法打开文件:", err)  
 return  
 }  
 defer file.Close()  
  
 // 读取文件内容  
 buffer := make([]byte, 1024)  
 for {  
 n, err := file.Read(buffer)  
 if err != nil && err.Error() != "EOF" {  
 fmt.Println("读取文件出错:", err)  
 return  
 }  
 if n == 0 {  
 break  
 }  
 fmt.Print(string(buffer[:n]))  
 }  
}

2. Use bufio package and Scanner type

The bufio package provides more advanced reading functions, among which the Scanner type can easily read the file content line by line. .

package main  
  
import (  
 "bufio"  
 "fmt"  
 "os"  
)  
  
func main() {  
 file, err := os.Open("file.txt")  
 if err != nil {  
 fmt.Println("无法打开文件:", err)  
 return  
 }  
 defer file.Close()  
  
 scanner := bufio.NewScanner(file)  
 for scanner.Scan() {  
 line := scanner.Text()  
 fmt.Println(line)  
 }  
 if err := scanner.Err(); err != nil {  
 fmt.Println("读取文件出错:", err)  
 }  
}

3. Use the ioutil package and the ReadFile function

The ioutil package provides some practical functions to process file contents, among which the ReadFile function can directly read the entire file. content and returns a byte slice. This method is suitable for reading smaller files.

package main  
  
import (  
 "fmt"  
 "io/ioutil"  
 "log"  
)  
  
func main() {  
 content, err := ioutil.ReadFile("file.txt")  
 if err != nil {  
 log.Fatal(err)  
 }  
 fmt.Println(string(content))  
}

4. Use a combination of os/exec package and command line tools to read the file content

For example, use the cat command to read the file content:

This method can read the file content by executing the command line tool, and is suitable for dynamically reading files at runtime. It should be noted that this method requires additional system calls and command line parameter processing. Therefore, the performance may not be as good as directly using the built-in functions of the Go language. But in some cases, using command line tools may be more flexible and convenient.

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