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I want to select a certain area of a TextBox control in asp.net WebForms application. The situation is that the textbox contains email addresses seperated by ;. I wrote a little MailValidator class that sorts out valid and invalid email addresses.

Now i want the wrong email address to be selected, so that the user can correct it right away. As i mentioned, I know which addresses are valid and which aren't.

How do I do that? I know how to select the whole text with .Focus() (works at least in IE, and that's enough) But how can I only select a certain area? Is TextBox.Text.Select<> the way to go? If so, can someone provide an example? I don't fully understand what .Select<> actually does.

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1  
TextBox.Text.Select<> is not for selecting perticular text inside a textbox. .Select<> is a projection operator that can be applied to any list or array. Since TextBox.Text returns a String i.e. a array of char type, so you are seeing Select<> in VS intellisence. It has nothing to do with selecting textbox data. So don't be cofused with that! –  Sanjeev Rai Jun 13 '13 at 7:16
    
Thanks. I already suspected that .Select<> has nothing to do with text selection. –  Mathew Jun 13 '13 at 7:38

1 Answer 1

up vote 0 down vote accepted

I think you need to use Javascript with this function, you just need to find the start and end of your selection.

function createSelection(field, start, end) {
    if( field.createTextRange ) {
      var selRange = field.createTextRange();
      selRange.collapse(true);
      selRange.moveStart('character', start);
      selRange.moveEnd('character', end);
      selRange.select();
      field.focus();
    } else if( field.setSelectionRange ) {
      field.focus();
      field.setSelectionRange(start, end);
    } else if( typeof field.selectionStart != 'undefined' ) {
      field.selectionStart = start;
      field.selectionEnd = end;
      field.focus();
    }
  }
share|improve this answer
    
Allright, so it's not possible with c#. Now I just have to figure out how to access javascript in asp.net (Yes, I am quite new to asp.net :) ) But I am sure that I will get there. Thanks for the Answer! I will report back later. –  Mathew Jun 13 '13 at 7:37
    
would that be something along the line: <asp:TextBox ID="txtAdditionalEmail" runat="server" TabIndex="130" Width="264px" CssClass="Feld2" onFocus="createSelection(frmTelefonzettel.txtAdditionalEmail.Text, 1, 5)" OnTextChanged="TextBox_TextChanged"></asp:TextBox> –  Mathew Jun 13 '13 at 8:18
    
Discregard this comment. The keyword 'this' was enough to tell the function which field i wanted to use. Thanks you very much for your help!! Question marked as answered. –  Mathew Jun 13 '13 at 8:38

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