How to remove all special characters from a string

protected string StripSpecChars(string txtIn)
{
    string txtOut = Regex.Replace(txtIn, @"[^\w\.@-]", "").Trim();
    return txtOut;        
}

How to remove commonly occuring English words from a string

I’m using this function to filter common words out of a search query.

protected string removeCommonWords(string sourceStr)
{
    string[] seperator = { " " };
    string[] ignoreWords = { "a", "all", "am", "an", "and", "any", "are", "as",
        "at", "be", "but", "can", "did", "do", "does", "for", "from", "had",
        "has", "have", "here", "how", "i", "if", "in", "is", "it", "no", "not",
        "of", "on", "or", "so", "that", "the", "then", "there", "this", "to",
        "too", "up", "use", "what", "when", "where", "who", "why", "you" };
    string[] outputStr = { };

    outputStr = sourceStr.ToLower().Split(seperator, StringSplitOptions.RemoveEmptyEntries);

    foreach (string unwantedWord in ignoreWords)
    {
        int index = Array.IndexOf(outputStr, unwantedWord);

        if (index != -1)
        {
            string[] copyStrArr = new string[outputStr.Length - 1];

            // copy the elements before the found index
            for (int i = 0; i < index; i++)
            {
                copyStrArr[i] = outputStr[i];
            }

            // copy the elements after the found index
            for (int i = index; i < copyStrArr.Length; i++)
            {
                copyStrArr[i] = outputStr[i + 1];
            }

            outputStr = copyStrArr;
        }
    }

    sourceStr = string.Join(" ", outputStr);

    return sourceStr;
}

Let me know if you guys have a better solution.

Strip out HTML tags using RegEx

This code will strip out all the HTML tags and truncate the text to 4 lines.

public static string TruncateText(string txtIn, int newLength)
{
    string txtOut = txtIn;
    string pattern = @"<(.|\n)*?>";

    //Strip out HTML tags
    if (Regex.IsMatch(txtIn, pattern, RegexOptions.None))
        txtOut = Regex.Replace(txtIn, pattern, string.Empty, RegexOptions.Multiline).Trim();

    if (txtOut.Length > newLength)
    {
        int endPos = txtOut.LastIndexOf(" ", newLength);
        txtOut = txtOut.Substring(0, endPos) + "...";
    }

    return txtOut;
}

Setting a default button in .NET

One way is to use a class like this to add an onkeydown client event to a to a textbox.

using System;
using System.Web.UI.WebControls;

namespace System.Web.UI.DefaultButton
{
      /// <summary>
      /// Methods to set default button
      /// </summary>
      class DefaultButton
      {
            /// <summary>
            /// Sets default button for the specified control
            /// </summary>
            Control name where user hits enter key</param>
            Button control to be called</param>
            void SetDefaultButton ( TextBox control , Button btButton )
            {
                  control.Attributes.Add("if(event.which ||
                  event.keyCode){if ((event.which == 13) ||
                  (event.keyCode == 13)) {document.getElementById('"+ btButton.ClientID+"').click();return false;}}
                  else {return true}; ");
            }

            /// <summary>
            /// Sets default button as the image button
            /// </summary>
            Control name where user hits enter key</param>
            Imagebutton to be called</param>
            void SetDefaultButton ( TextBox control , ImageButton btButton )
            {
                  control.Attributes.Add("if(event.which ||
                  event.keyCode){if ((event.which == 13) ||
                  (event.keyCode == 13)) {document.getElementById('"+ btButton.ClientID+"').click();return false;}}
                  else {return true}; ");
            }
      }
}

Another easier and quicker alternative is to place all the form elements in an ASP.NET Panel and then define the panel’s default button property, like this:

<asp:Panel runat="btnHello">
    First name: <asp:TextBox runat="txtFirstName" />
    <asp:ImageButton ID="lbHello_Click" />
</asp:Panel><br /><br />

But of course if you are using a LinkButton, then its a whole another ball game. None of the techniques described above might work for you. But you are in luck, this page has what you need to get around that - Using Panel.DefaultButton property with LinkButton control in ASP.NET

Recursive Goodness - II

Find a control within a control recursively:

protected void Control FindControlRecursive(Control Root, string Id)
{
    if (Root.ID == Id)
    return Root;
    foreach (Control Ctl in Root.Controls)
    {
        Control FoundCtl = FindControlRecursive(Ctl, Id);
        if (FoundCtl != null)
        return FoundCtl;
    }
    return null;
}