Regular Expressions in C# (RegEx)

While working with several code-cleanup regular expressions, I had a thought of putting together a collection of nifty and useful patterns that I could use latter when the time came so I and anyone else wouldn't need to rebuild or re-research them.

The list is small for now, but I will try to add to it in time... If you have useful expression not listed here, do share!

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• {([^{]*?)}
• This expression matches the objects contents from left curly bracket to the right and returns the body within the brackets $1.
• If implemented properly in a source code bottom-up decomposer, this expression will be able to help break a string into a tree of objects (TreeNode)
• \{((?>[^{}]+|\{(?<DEPTH>)|\}(?<-DEPTH>))*(?(DEPTH)(?!)))\} by Tim Pietzcker on StackOverflow
• This does the same as the above except that it also includes embedded objects.
• If implemented properly in a source code top-down decomposer, this expression will be able to help break a string into a tree of objects (TreeNode)

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• ^([\w\.\-]+)@([\w\-]+)((\.(\w){2,3})+)$
• This expression matches valid emails.

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• (?<=<body([^<]*?)>)[\s\S]*(?=</body>)
• Extract HTML body using Look-ahead and Look-behind.
• (<script([^<]*?)>[\s\S]*?</script>)
• Select SCRIPT block within body of HTML.

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• [\n]+
• Remove multiple newline characters: '\n\n\n' => '\n' (replace '\n' with any other character to do the same: [ab]+ => 'aaabbb' => 'ab')

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• "[^\\"]*(?:(?:\\\\)*(?:\\"[^\\"]*)?)*" Hatchi on StackOverflow
• Capture a string with an embedded string - used for parsing source code. (This one took me some time to find!)
• \"([^\"]+)\"
• Capture every other matching string.
  Example: "my"string"has"quotes"!" → { my, has, ! } and not { string, quotes }.

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• (?<=^)
• Match patterns at the beginning of a string using the 'look-behind' expression combined with the carrot character delimiter.


I wrote a simple WinForms App to test my expressions on so I would know if they would work the way I intended them to. This editor was also built to apply the expression on the given text, a file, or a tree of files of a given file extension. There is the option to Replace, Capitalize, Lowercase, and Invert-Case.

The code in this picture is partially parsed java code. Though I am capable of manually parsing Java code to CSharp, it becomes a tedious chore that consomes too much time when there are over 1.2 thousand files to port (and a simple String.Replace will not do the trick - too many variables to consider)!