Reading and Writing File

The Design view of that Page
Write the value in the TextBox
<asp:TextBox ID="tbxWrite" runat="server"></asp:TextBox>
<asp:Button ID="btnWrite" runat="server" Text="Write"
OnClick="btnWrite_Click" />
<br />
Read all that value are written in the Textbox
<asp:Button ID="btnRead" runat="server" Text="Read" OnClick="btnRead_Click" />
<asp:Literal ID="litText" runat="server"></asp:Literal>



The Code Behind of that Page

string contents = "";
string fileNameWithPath=@"c:\sample.txt";//where ur text file is present
protected void Page_Load(object sender, EventArgs e)
{
}
protected void btnWrite_Click(object sender, EventArgs e)
{
//This will be used to write the file
using (StreamWriter writer = File.AppendText(fileNameWithPath))
{
//whatever u write in that textbox it will write on to that text file
writer.Write(tbxWrite.Text);
}
}

protected void btnRead_Click(object sender, EventArgs e)
{
// Read data from text file
using (StreamReader reader = File.OpenText(fileNameWithPath))
{
// reads a single line of contents
contents = reader.ReadLine();
// reads complete contents of the the file
contents += reader.ReadToEnd();
}
litText.Text = contents;
}