Regex Utilities

using System;
using System.Globalization;
using System.Text.RegularExpressions;




public class RegexUtilities
{
bool invalid = false;

public bool IsValidEmail(string strIn)
{
invalid = false;
if (String.IsNullOrEmpty(strIn))
return false;

// Use IdnMapping class to convert Unicode domain names.
try
{
strIn = Regex.Replace(strIn, @”(@)(.+)$”, this.DomainMapper,
RegexOptions.None, TimeSpan.FromMilliseconds(200));
}
catch (RegexMatchTimeoutException)
{
return false;
}

if (invalid)
return false;

// Return true if strIn is in valid e-mail format.
try
{
return Regex.IsMatch(strIn,
@”^(?(“”)(“”[^””]+?””@)|(([0-9a-z]((\.(?!\.))|[-!#\$%&’\*\+/=\?\^`\{\}\|~\w])*)(?<=[0-9a-z])@))" + @"(?(\[)(\[(\d{1,3}\.){3}\d{1,3}\])|(([0-9a-z][-\w]*[0-9a-z]*\.)+[a-z0-9]{2,24}))$", RegexOptions.IgnoreCase, TimeSpan.FromMilliseconds(250)); } catch (RegexMatchTimeoutException) { return false; } }


private string DomainMapper(Match match)
{
// IdnMapping class with default property values.
IdnMapping idn = new IdnMapping();

string domainName = match.Groups[2].Value;
try
{
domainName = idn.GetAscii(domainName);
}
catch (ArgumentException)
{
invalid = true;
}
return match.Groups[1].Value + domainName;
}
}