using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"(?:^|(?<=\s))(?!1?\d{10}@)(\w[\w\.]*@\w+\.[\w\.]+)\b";
string input = @"123456789@test.com // allowed (9 digits or less)
01234567890@test.com // allowed (11 digits but not starting with 1)
123456789012@test.com // allowed (12 digits or more)
0123456789@test.com // NOT allowed (10 digits)
11234567890@test.com // NOT allowed (11 digits and starting with 1)";
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