using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"^((?:[A-Za-z0-9!#$%&'*+\-\/=?^_`{|}~]|(?<=^|\.)""|""(?=$|\.|@)|(?<="".*)[ .](?=.*"")|(?<!\.)\.){1,64})(@)((?:[A-Za-z0-9.\-])*(?:[A-Za-z0-9])\.(?:[A-Za-z0-9]){2,})$";
string input = @"Valid email addresses
simple@example.com
very.common@example.com
disposable.style.email.with+symbol@example.com
other.email-with-hyphen@example.com
fully-qualified-domain@example.com
user.name+tag+sorting@example.com
(may go to user.name@example.com inbox depending on mail server)
x@example.com
(one-letter local-part)
example-indeed@strange-example.com
example@s.example
(see the List of Internet top-level domains)
"" ""@example.org
(space between the quotes)
""john..doe""@example.org
(quoted double dot)
=============================================================
Invalid email addresses
Abc.example.com
(no @ character)
A@b@c@example.com
(only one @ is allowed outside quotation marks)
a""b(c)d,e:f;g<h>i[j\k]l@example.com
(none of the special characters in this local-part are allowed outside quotation marks)
just""not""right@example.com
(quoted strings must be dot separated or the only element making up the local-part)
this is""not\allowed@example.com
(spaces, quotes, and backslashes may only exist when within quoted strings and preceded by a backslash)
this\ still\""not\\allowed@example.com
(even if escaped (preceded by a backslash), spaces, quotes, and backslashes must still be contained by quotes)
1234567890123456789012345678901234567890123456789012345678901234+x@example.com
(local part is longer than 64 characters)";
RegexOptions options = RegexOptions.Multiline;
foreach (Match m in Regex.Matches(input, pattern, options))
{
Console.WriteLine("'{0}' found at index {1}.", m.Value, m.Index);
}
}
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for C#, please visit: https://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex(v=vs.110).aspx