Regular expression is not only difficult to write it correctly but also because we don’t have time to study details of a specification of the expression we want to validate. So I try to collect as much as I can common used regex for reference.

using System;
using System.Text.RegularExpressions;

public class GeneralValidation
{

public static bool IsEmail(string Email)
{
string strRegex = @"^([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}" +
@"\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\" +
@".)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$";
Regex re = new Regex(strRegex);
if (re.IsMatch(Email))
return (true);
else
return (false);
}

public static bool IsUrl(string Url)
{
string strRegex = "^(https?://)"
+ "?(([0-9a-z_!~*'().&=+$%-]+: )?[0-9a-z_!~*'().&=+$%-]+@)?" //user@
+ @"(([0-9]{1,3}\.){3}[0-9]{1,3}" // IP- 199.194.52.184
+ "|" // allows either IP or domain
+ @"([0-9a-z_!~*'()-]+\.)*" // tertiary domain(s)- www.
+ @"([0-9a-z][0-9a-z-]{0,61})?[0-9a-z]\." // second level domain
+ "[a-z]{2,6})" // first level domain- .com or .museum
+ "(:[0-9]{1,4})?" // port number- :80
+ "((/?)|" // a slash isn't required if there is no file name
+ "(/[0-9a-z_!~*'().;?:@&=+$,%#-]+)+/?)$";
Regex re = new Regex(strRegex);

if (re.IsMatch(Url))
return (true);
else
return (false);
}
}