Golang : bufio.NewReader.ReadLine to read file line by line

In the previous tutorial on how to read file line by line with bufio.NewScanner() example. The previous example that use bufio.NewScanner() will throw token too long error message if attempt to read a very large file. You can see the details here.

This tutorial will show you another way to read file line by line, but with bufio.NewReader() and ReadLine() method instead.

 package main

 import (
 "bufio"
 "flag"
 "fmt"
 "io"
 "os"
 )

 func main() {
 flag.Parse()

 filename := flag.Arg(0)

 file, err := os.Open(filename)
 if err != nil {
 panic(err)
 }

 defer file.Close()

 reader := bufio.NewReader(file)

 for {
 line, _, err := reader.ReadLine()

 if err == io.EOF {
 break
 }

 fmt.Printf("%s \n", line)
 }
 }

Go run this file with the filename as 1st parameter and it will print out each line to the screen.

Happy coding!

References :

Get command line arguments

Read file with Golang