Mastering Windows PowerShell Scripting - Third Edition

Debugging regular expressions

Regular expressions can quickly become complicated and difficult to understand. Modifying a complex regular expression isn't a particularly simple undertaking.

While PowerShell indicates whether there's a syntax error in a regular expression, it can't do more than that. For example, in the following expression, PowerShell announces that there is a syntax error:

PS> 'abc' -match '*'parsing "*" - Quantifier {x,y} following nothing.At line:1 char:1+ 'abc' -match '*'+ ~~~~~~~~~~~~~~~~    + CategoryInfo : OperationStopped: (:) [], ArgumentException    + FullyQualifiedErrorId : System.ArgumentException 

Fortunately, there are a number of websites that can visualize a regular expression and lend an understanding of how it ...