using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"^[a-z0-9]+(?!.*(?:\+{2,}|\-{2,}|\.{2,}))(?:[\.+\-]{0,1}[a-z0-9])*@gmail\.com$";
string input = @"niceandsimple@gmail.com
very.common@gmail.com
disposable.style.email.with+symbol@gmail.com
other.email-with-dash@gmail.com
invalid--email@gmail.com
invalid++email@gmail.com
invalid..email@gmail.com
-invalid-email@gmail.com
invalid--email-@gmail.com";
RegexOptions options = RegexOptions.Multiline | RegexOptions.IgnoreCase;
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