How to use C# FileStream Class

The FileStream Class represents a File in the Computer. Use the FileStream class to read from, write to, open, and close files on a file system, as well as to manipulate other file related operating system handles including pipes, standard input, and standard output. FileStream allows to move data to and from the stream as arrays of bytes. We operate File using FileMode in FileStream Class

Some of FileModes as Follows :

  1. FileMode.Append : Open and append to a file if the file does not exist , it create a new file.

  2. FileMode.Create : Create a new file , if the file exist it will append to it.

  3. FileMode.CreateNew : Create a new File , if the file exist , it throws exception.

  4. FileMode.Open : Open an existing file.

How to create a file using C# FileStream Class?

The following C# example shows , how to create and write in a file using FileStream.

using System;
using System.Windows.Forms;
using System.IO;
using System.Text;

namespace WindowsApplication1
    public partial class Form1 : Form
        public Form1()

        private void button1_Click(object sender, EventArgs e)
                System.IO.FileStream wFile;
                byte[] byteData = null;
                byteData = Encoding.ASCII.GetBytes("FileStream Test");
                wFile = new FileStream("c:\\streamtest.txt", FileMode.Append);
                wFile.Write(byteData, 0, byteData.Length);
            catch (IOException ex)

When we execute the above C# source code , it create a new File and write the content to the specified path . (C) 2021    Founded by raps mk
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