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Posted 15 Jan 2006
Licenced CPOL


, 15 Jan 2006
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An object that makes it easy to extract information from strings, especially HTML content.


StringParser is an object that helps you extract information from a string.  The class is perhaps best suited to parse HTML pages downloaded from the web (see my WebResourceProvider class that helps you do this).  You use StringParser by constructing it with some content (i.e. a string) and using its navigational and extraction methods to extract substrings from the content.  StringParser also provides some static methods designed specifically for parsing HTML.


Here are some of the methods provided by StringParser.  Please see the accompanying documentation for an exhaustive list.

Navigational API
 Extraction API
 Position query API
 HTML parsing API

Example 1 - Extracting delimited text

This example shows how to extract text contained between two delimiters. 
// Extract text between the comma and question mark
string strExtract = "";
string str = "Hello Sally, how are you?";
StringParser p = new StringParser (str);
if (p.skipToStartOf (",") && p.extractTo ("?", ref strExtract))
   Console.Writeln ("Extracted text = {0}", strExtract);
   Console.Writeln ("No text extracted.");

Example 2 - Extracting the nth occurence of a delimited string

This example shows how to obtain the href attribute of the third anchor tag (<a>) in an HTML string.  The example assumes the string contains valid HTML.
// Get href attribute of 3rd <a> tag
string strExtract = "";
string str = "..."; // HTML
StringParser p = new StringParser (str);
if (p.skipToStartOfNoCase ("<a") &&
    p.skipToStartOfNoCase ("<a") &&
    p.skipToStartOfNoCase ("<a") &&
    p.skipToStartOfNoCase ("href=\"") &&
    p.extractTo ("\"", ref strExtract))
   Console.Writeln ("Extracted text = {0}", strExtract);
   Console.Writeln ("No text extracted.");

Example 3 - Global case-insensitive replacement

This example shows how to case-insensitively replace a string in the parser's content..
// Replace every occurence of <td> with <td class="foo">
string str = "..."; // HTML
StringParser p = new StringParser (str);
p.replaceEvery ("<td>", "<td class=\"foo\">");

Example 4 - Poor man's web scraping

This example shows how to obtain a stock's quote from the content downloaded from Yahoo Finance (MSFT).  The example makes assumptions about the format of the web page.
// Scrape
string strQuote = "";
string str = "..."; // HTML downloaded from
StringParser p = new StringParser (str);
if (p.skipToEndOfNoCase ("Last Trade:</td><td class="yfnc_tabledata1"><big><b>") &&
    p.extractTo ("</b>", ref strQuote))
   Console.Writeln ("MSFT (delayed) = {0}", strQuote);

Example 5 - Get list of hyperlinked phrases

This example shows how to obtain the list of hyperlinked phrases in HTML content.
ArrayList phrases = new ArrayList();
string str = "..."; // HTML content
StringParser p = new StringParser (str);
while (p.skipToStartOfNoCase ("<a")) {
  string strPhrase = "";
  if (p.skipToEndOf (">") && p.extractTo ("<a>", ref strPhrase))
     phrases.Add (strPhrase);

Demo applications

C# applications (with full source code) that use StringParser can be found here:

Revision History

  • 15 Jan 2006
    Initial version.


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Ravi Bhavnani
Technical Lead
Canada Canada
Ravi Bhavnani is an ardent fan of Microsoft technologies who loves building Windows apps, especially PIMs, system utilities, and things that go bump on the Internet. During his career, Ravi has developed expert systems, desktop imaging apps, marketing automation software, EDA tools, a platform to help people find, analyze and understand information, trading software for institutional investors and advanced data visualization solutions. He currently works for a company that provides enterprise workforce management solutions to large clients.

His interests include the .NET framework, reasoning systems, financial analysis and algorithmic trading, NLP, HCI and UI design. Ravi holds a BS in Physics and Math and an MS in Computer Science and was a Microsoft MVP (C++ and C# in 2006 and 2007). He is also the co-inventor of 3 patents on software security and generating data visualization dashboards. His claim to fame is that he crafted CodeProject's "joke" forum post icon.

Ravi's biggest fear is that one day he might actually get a life, although the chances of that happening seem extremely remote.

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Comments and Discussions

GeneralExtracting Meta Keywords and Descriptions Pin
keith_fra26-Jul-07 9:48
memberkeith_fra26-Jul-07 9:48 

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