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Golang program to write data into the file using buffer writer

Here, we are going to learn how to write data into the file using buffer writer in Golang (Go Language)?
Submitted by Nidhi, on April 08, 2021 [Last updated : March 04, 2023]

Writing data into the file using buffer writer in Golang

Problem Solution:

In this program, we will open a file and create a buffer-writer using a file pointer and then write data into the file using buffer writer into a file.

Program/Source Code:

The source code to write data into a file using buffer writer is given below. The given program is compiled and executed on the ubuntu 18.04 operating system successfully.

Golang code to write data into the file using buffer writer

// Golang program to write data into a file
// using buffer writer

package main

import "fmt"
import "os"
import "bufio"

func main() {
	filePtr, err := os.OpenFile("Demo.txt", os.O_WRONLY, 0666)

	if err != nil {
		fmt.Println(err)
	}

	//Create a buffer writter using file pointer.
	bufferedWriter := bufio.NewWriter(filePtr)

	len1, err := bufferedWriter.Write([]byte{10, 20, 30, 40, 50})
	if err != nil {
		fmt.Println(err)
	}
	fmt.Printf("%d bytes written into file\n", len1)

	len2, err := bufferedWriter.WriteString("Hello World\n")
	if err != nil {
		fmt.Println(err)
	}
	fmt.Printf("%d bytes written into file\n", len2)

	bufferedWriter.Flush()
	filePtr.Close()
}

Output:

5 bytes written into file
12 bytes written into file

Explanation:

In the above program, we declare the package main. The main package is used to tell the Go language compiler that the package must be compiled and produced the executable file. Here, we imported the fmt, os packages then we can use a function related to the fmt and os package.

Here, we also imported the bufio package to use buffer writer to write data into a file.

In the main() function, we opened the "Demo.txt" file and then created a buffered writer using bufio.NewWriter() function. Then write data into the file using buffer writer into a file.

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