how to get only selected text in multimode textbox in asp.net in c#

This may help U

http://social.msdn.microsoft.com/Forums/en-US/winforms/thread/c93fdeec-0251-498c-b910-80cdf6debef3[^]

What is the exact requirement, just think on it, and if you have an option then go for a richtext editor.

Which will help you to make a good contol over the text other than only the font you can also make it bold, italic..... etc

Hope this[^] might help you.

Try This...

<form id="form1" runat="server">
<div>
<asp:TextBox runat="server" ID="txt1" TextMode="MultiLine" />
<asp:HiddenField runat="server" ID="hidSelectedText" />
<asp:Button runat="server" ID="showselected" Text="Show selected" OnClientClick="doselection();" OnClick="showselected_Click" />
<script type="text/javascript">
function doselection()
{
if (window.getSelection)
{
txt = window.getSelection();
}
else if (document.getSelection)
{
txt = document.getSelection();
}
else if (document.selection)
{
txt = document.selection.createRange().text;
}
else
{
alert('selection not supported');
}
document.getElementById('<%=hidSelectedText.ClientID %>').value = txt;
}
</script>
</div>
</form>

protected void showselected_Click(object sender, EventArgs e)
{

Response.Write(hidSelectedText.Value);

}

for that you should have RichTextBox.........

public void CreateMyRichTextBox()
{
    RichTextBox richTextBox1 = new RichTextBox();
    richTextBox1.Dock = DockStyle.Fill;

    richTextBox1.LoadFile("C:\\MyDocument.rtf");
    richTextBox1.Find("Text", RichTextBoxFinds.MatchCase);
    richTextBox1.SelectionFont = new Font("Verdana", 12, FontStyle.Bold);
    richTextBox1.SelectionColor = Color.Red;
    richTextBox1.SaveFile("C:\\MyDocument.rtf", RichTextBoxStreamType.RichText);
    this.Controls.Add(richTextBox1);
}

Or see this link

Like BobJanovas says, you cannot have multiples font in a textbox. If you don't want to implement a rich editor, you can implement a "preview" panel like CodeProject does.

Here you got a good Rich Text Editor:
http://ckeditor.com/[^]

It's free. I used it. It's really good

If you need more help, please let me know.

Regards.

Use
Request.Form["idofTextbox"];
dont use idoftext.text here..it doesnt contain updated value..Hope it solves ur problem.. :)