using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"</h1>\s*(<div>)?(.*?)\s*(</div>)?</header>";
string input = @"<header><h1>A Suspenseful Movie Title</h1><div>The narrative traces the journey of three youngsters from a seaside community who inadvertently capture a homicide on camera. As they unwittingly become enmeshed with the perpetrator, it unravels a convoluted case that entangles numerous families, culminating in an unpredictable outcome.</div></header>
<header>
<h1>Movie Title</h1>
A group of extraordinary individuals, each with unconventional occupations, emerged as champions for the common people on the streets by pursuing justice. Suddenly, they gained access to supernatural abilities.
</header>
<header>
<h1>Funny Comedy Movie Title</h1>The following is a comical tale of a husband and wife's pursuit of their ambition to obtain a flat.</header>";
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