using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"^(?:ISBN(?:-13)?:? )?(?<gs1>\d{3})(?:(?<number>\d{9})|(?=[\d -]{14}$)[ -](?<registrationGroup>\d{1,5})[ -](?<registrant>\d{1,7})[ -](?<publication>\d{1,6})[ -])(?<checkDigit>\d)$";
string input = @"9781861978769
97818619787659
978186197879
978-1-86197-876-9
978-1-86197-87-9
978-1-86197-8765-9
978-186197-876-9
978-186197-8-76-9";
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