using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"((?<ID>[2-9]{1}[0-9]{3}\s?[0-9]{4}\s?[0-9]{4}\s?)(?&ID){20,})";
string input = @"2453 1234 4367 2453 1234 4367 2453 1234 4367 2453 1234 4367 2453 1234 4367 2453 1234 4367 2453 1234 4367 2453 1234 4367 2453 1234 4367 2453 1234 4367 2453 1234 4367 2453 1234 4367 2453 1234 4367 2453 1234 4367 2453 1234 4367 2453 1234 4367 2453 1234 4367 2453 1234 4367 2453 1234 4367 2453 1234 4367 2453 1234 4367 ";
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