C# Title From HTML

HTML documents have title elements. The data in title elements is important. It is used for search-engine optimization and RSS feeds. We see a simple but capable C# method of extracting the TITLE elements from HTML documents. It uses regular expressions.

Example

Here we look at how you can the contents of the TITLE element from your HTML. This is important for SEO and making sure your HTML is correct. After the code, we see the Regex parts in detail and more factors.

This C# example program gets the HTML title from strings. It uses Regex.

Program that gets TITLE element from HTML [C#]

using System;
using System.IO;
using System.Text.RegularExpressions;

class Program
{
    static void Main()
    {
	// Read in an HTML file.
	string html = File.ReadAllText("Problem.html");

	// Get the title of the HTML.
	Console.WriteLine(GetTitle(html));

	// End.
	Console.ReadLine();
    }

    /// <summary>
    /// Get title from an HTML string.
    /// </summary>
    static string GetTitle(string file)
    {
	Match m = Regex.Match(file, @"<title>\s*(.+?)\s*</title>");
	if (m.Success)
	{
	    return m.Groups[1].Value;
	}
	else
	{
	    return "";
	}
    }
}

Output

Title of the Page

Description. This is a console application written in the C# language that first gets the first TITLE element from the HTML file, and then prints it to the console. The application must have the specified HTML file present in the current directory.

Regular expressions

Here we look at descriptions of the regular expressions used in the above C# program. The regular expressions look for a start tag and an end tag. They also ignore whitespace between the inner parts of the tags and the string.

Symbol: Description

@           Uses special string syntax.
\s*         Matches 0 or more spaces.
(.+?)       Matches text but isn't greedy.
	    Stops as soon as it can.
\s*         Matches 0 or more spaces.

Match       C# regular expression object.
Groups[1]   First group found in input.
	    Starts at 1.
Value       String value of Group.

Bugs

This code is not flexible enough for some HTML documents. For example, the program won't work for complicated HTML, such as HTML that uses attributes heavily. However, the code that matches TITLE should work for all XHTML. Additionally, they assume the HTML is lowercase, although this could be easily changed.

You can make more capable versions of this method. However, the code is like this because I didn't want a more powerful solution. It is easier to detect small errors if your code doesn't try to deal with them.

Summary

We can capture the contents of the TITLE and paragraph elements from HTML documents using the C# language. Every webmaster in the world should know that the TITLE is important. You can use regular expressions like these for reading important elements from your HTML.