How to: Write Text to a File

.NET Framework Developer's Guide

The following code examples show how to write text to a text file.

The first example shows how to add text to an existing file. The second example shows how to create a new text file and write a string to it. Similar functionality can be provided by the WriteAllText methods.

Note:
Visual Basic users may choose to use the methods and properties provided by the My.Computer.FileSystem object for file I/O. For more information, see My.Computer.FileSystem Object.

Example

Visual Basic

Imports System
Imports System.IO

Class Test
    Public Shared Sub Main()
        ' Create an instance of StreamWriter to write text to a file.
        Using sw As StreamWriter = New StreamWriter("TestFile.txt")
            ' Add some text to the file.
            sw.Write("This is the ")
            sw.WriteLine("header for the file.")
            sw.WriteLine("-------------------")
            ' Arbitrary objects can also be written to the file.
            sw.Write("The date is: ")
            sw.WriteLine(DateTime.Now)
            sw.Close()
        End Using
    End Sub
End Class

using System;
using System.IO;

class Test 
{
    public static void Main() 
    {
        // Create an instance of StreamWriter to write text to a file.
        // The using statement also closes the StreamWriter.
        using (StreamWriter sw = new StreamWriter("TestFile.txt")) 
        {
            // Add some text to the file.
            sw.Write("This is the ");
            sw.WriteLine("header for the file.");
            sw.WriteLine("-------------------");
            // Arbitrary objects can also be written to the file.
            sw.Write("The date is: ");
            sw.WriteLine(DateTime.Now);
        }
    }
}

Visual Basic

Option Explicit On 
Option Strict On
Imports System
Imports System.IO
Public Class TextToFile
    Private Const FILE_NAME As String = "MyFile.txt"
    Public Shared Sub Main()
        If File.Exists(FILE_NAME) Then
            Console.WriteLine("{0} already exists.", FILE_NAME)
            Return
        End If
        Using sw As StreamWriter = File.CreateText(FILE_NAME)
            sw.WriteLine("This is my file.")
            sw.WriteLine("I can write ints {0} or floats {1}, and so on.", 1, 4.2)
            sw.Close()
        End Using
    End Sub
End Class

using System;
using System.IO;
public class TextToFile 
{
    private const string FILE_NAME = "MyFile.txt";
    public static void Main(String[] args) 
    {
        if (File.Exists(FILE_NAME)) 
        {
            Console.WriteLine("{0} already exists.", FILE_NAME);
            return;
        }
        using (StreamWriter sw = File.CreateText(FILE_NAME))
        {
            sw.WriteLine ("This is my file.");
            sw.WriteLine ("I can write ints {0} or floats {1}, and so on.", 
                1, 4.2);
            sw.Close();
        }
    }
}

Tasks

Concepts

Reference