--- title: "When Regular Expressions Attack" url: "https://osherove.com/blog/2004/3/30/when-regular-expressions-attack.md" canonical: "https://osherove.com/blog/2004/3/30/when-regular-expressions-attack.html" published: "2004-03-30T13:31:00" updated: "2004-03-30T13:31:00" tags: [".Net Quotations"] author: "Roy Osherove" description: "It's not that I'm BAD at regular expressions, I just learn enough to get me by when I need them. I'm nothing like Darren, who decided to do something like this : While reading the VB Language Spec today I decided to…" usage: "Licensed under CC BY 4.0 — reuse, quote and adapt with attribution (Roy Osherove, link to the original page)." license: "https://creativecommons.org/licenses/by/4.0/" --- # When Regular Expressions Attack By Roy Osherove March 30, 2004 In [.Net Quotations](https://osherove.com/blog/category/net-quotations) **Historical article** · Originally published March 30, 2004; technical details may be outdated. It's not that I'm BAD at regular expressions, I just learn enough to get me by when I need them. I'm nothing like Darren, [who decided to do something like this](http://blogs.regexadvice.com/DNeimke/posts/873.aspx): _While reading the VB Language Spec today I decided to attempt to follow the grammar syntax for matching DateTime Literals:_     [_http://msdn.microsoft.com/library/en-us/vbls7/html/vblrfvbspec2\_4\_6.asp?frame=true_](http://msdn.microsoft.com/library/en-us/vbls7/html/vblrfvbspec2_4_6.asp?frame=true) _The resulting pattern can be seen (fully commented) here:_     [_http://www.regexlib.com/REDetails.aspx?regexp\_id=638_](http://www.regexlib.com/REDetails.aspx?regexp_id=638) OK. I can't resist. Here's the full pattern (and it looks great in [The Regulator](http://royo.is-a-geek.com/regulator)): ``` (?'DateLiteral' (?# Per the VB Spec : DateLiteral ::= '#' [ Whitespace+ ] DateOrTime [ Whitespace+ ] '#' ) \#\s* (?'DateOrTime' (?# DateOrTime ::= DateValue Whitespace+ TimeValue | DateValue | TimeValue ) (?'DateValue' (?# DateValue ::= Whitespace+ TimeValue | DateValue | TimeValue ) ( (?# DateValue ::= MonthValue / DayValue / YearValue | MonthValue - DayValue - YearValue ) (?'Month'(0?[1-9])|1[0-2]) (?# Month 01 - 12 ) (?'Sep'[-/]) (?# Date separator '-' or '/' ) (?'Day'0?[1-9]|[12]\d|3[01]) (?# Day 01 - 31 ) \k'Sep' (?# whatever date separator was previously matched ) (?'Year'\d{1,4}) \s+ (?# TimeValue ::= HourValue : MinuteValue [ : SecondValue ] [ WhiteSpace+ ] [ AMPM ] ) (?'HourValue'(0?[1-9])|1[0-9]|2[0-4]) (?# Hour 01 - 24 ) [:] (?'MinuteValue'0?[1-9]|[1-5]\d|60) (?# Minute 01 - 60 ) [:] (?'SecondValue':0?[1-9]|[1-5]\d|60)? (?# Optional Minute :01 - :60 ) \s* (?'AMPM'[AP]M)? ) | ( (?# DateValue ::= MonthValue / DayValue / YearValue | MonthValue - DayValue - YearValue ) (?'Month'(0?[1-9])|1[0-2]) (?# Month 01 - 12 ) (?'Sep'[-/]) (?# Date separator '-' or '/' ) (?'Day'0?[1-9]|[12]\d|3[01]) (?# Month 01 - 31 ) \k'Sep' (?# whatever date separator was previously matched ) (?'Year'\d{4}) ) | ( (?# TimeValue ::= HourValue : MinuteValue [ : SecondValue ] [ WhiteSpace+ ] [ AMPM ] ) (?'HourValue'(0?[1-9])|1[0-9]|2[0-4]) (?# Hour 01 - 24 ) [:] (?'MinuteValue'0?[1-9]|[1-5]\d|60) (?# Minute 01 - 60 ) [:] (?'SecondValue':0?[1-9]|[1-5]\d|60)? (?# Optional Minute :01 - :60 ) \s* (?'AMPM'[AP]M)? ) ) ) \s*\# ) ``` ## More in .Net Quotations [All posts in .Net Quotations](https://osherove.com/blog/category/net-quotations) - Apr 3, 2004 ### [True Binary Serialization and Compression of Datasets](https://osherove.com/blog/2004/4/3/true-binary-serialization-and-compression-of-datasets.html) - Apr 3, 2004 ### [DPack: Free enhancement Add-ins to VS.NET IDE](https://osherove.com/blog/2004/4/3/dpack-free-enhancement-add-ins-to-vsnet-ide.html) - Mar 28, 2004 ### [Low defect rates are not a myth](https://osherove.com/blog/2004/3/28/low-defect-rates-are-not-a-myth.html) - Mar 27, 2004 ### [VS-Styler :Toggle and save your VS.Net font and color settings instantly](https://osherove.com/blog/2004/3/27/vs-styler-toggle-and-save-your-vsnet-font-and-color-settings.html) --- ## About the author **Roy Osherove**: Senior Solutions Architect at AWS working on AI for production and AI-driven development; author of The Art of Unit Testing and Elastic Leadership, with about 20 years of consulting and training on unit testing, TDD, team leadership and continuous delivery. ### Sites - [RobotPaper](https://robotpaper.ai/): This blog: AI patterns and anti-patterns, AI and coding agents, and engineering leadership. - [osherove.com](https://osherove.com): Roy's personal site. Author of The Art of Unit Testing and Elastic Leadership; consulting and training on unit testing, TDD, team leadership and continuous delivery, plus about 20 years of blog posts. - [The Art of Unit Testing](https://www.artofunittesting.com): The Art of Unit Testing, 3rd Edition (Manning): readable, maintainable, trustworthy unit tests, plus TDD workshops in C#, JavaScript, Java and Kotlin. - [5whys.com](https://www.5whys.com): Roy's writing on software team leadership: self-organizing teams, surviving chaos, learning mode and the Elastic Leadership model. - [Pipeline Driven](https://pipelinedriven.org): Continuous delivery and DevOps practices: build patterns, pipeline-friendly testing, DevOps metrics and enterprise DevOps. - [Elastic Leadership](https://www.elasticleadership.com): Elastic Leadership, Roy's framework for software team leaders (survival, learning and self-organizing modes). ### Social - X: https://x.com/royosherove - LinkedIn: https://www.linkedin.com/in/osherove/ ### Contact - Contact form: https://forms.gle/jQSx5KoXvrVA1JCK7 ### License Licensed under CC BY 4.0 — reuse, quote and adapt with attribution (Roy Osherove, link to the original page). License: https://creativecommons.org/licenses/by/4.0/