Regular expressions

Regular expressions describe patterns in strings that can be used in order to determine whether a given pattern occurs in a text or not.

In TreeSize, regular expressions can be used to find specific files and / or folders that match the criteria specified by regular expressions. A list of special characters are supported.

The following table shows some of the most used syntax and provides a few examples:

Expression	Syntax	Description	Example
Any character	.	Matches any single character except a line break.	a.o matches “aro” in “around” and “abo” in “about” but not “acro” in “across”.
Zero or more	*	Matches zero or more occurrences of the preceding expression, and makes all possible matches.	a*b matches “b” in “bat” and “ab” in “about”. e.*e matches the word “enterprise”.
One or more	+	Matches at least one occurrence of the preceding expression.	ac+ matches words that contain the letter “a” and at least one instance of “c”, such as “race” and “ace”. a.+s matches the word “access”.
Start of string	^	Matches the start of a string.	^[0-9] matches strings that start with a digit.
End of string	$	Matches the end of a string.	exe$ matches strings that end with “exe”.
Beginning of word	[[:<:]]	Matches only when a word starts at this point in the text.	[[:<:]]in matches words such as “inside” and “into” that begin with the letters “in”.
End of word	[[:>:]]	Matches only when a word ends at this point in the text.	ss[[:>:]] matches words such as “across” and “loss” that end with the letters “ss”.
Any one character in the set	[]	Matches any one of the characters in the []. To specify a range of characters, list the starting and ending characters separated by a dash (-), as in [a-z].	be[n-t] matches “bet” in “between”, “ben” in “beneath”, and “bes” in “beside” but not “bel” in “below”.
Any one character not in the set	[^...]	Matches any character that is not in the set of characters that follows the ^.	be[^n-t] matches “bef” in “before”, “beh” in “behind”, and “bel” in “below”, but not “ben” in “beneath”.
Or	|	Matches either the expression before or the one after the OR symbol (|). Mostly used in a group.	(sponge|mud) matches “sponge bath” and “mud bath”.
Escape character	\	Matches the character that follows the backslash (\) as a literal. This lets you find the characters that are used in regular expression notation, such as { and ^.	\^ searches for the ^ character.
Repeat n times	{n}	Matches n occurrences of the preceding expression.	[0-9]{4} matches any 4-digit sequence.
Grouping	()	Lets you group a set of expressions together. If you want to search for two different expressions in a single search, you can use the Grouping expression to combine them.	If you want to search for [a-z][1-3] or [0-9][a-z], you would combine them: ([a-z][1-3])|([0-9][a-z]).

More examples

Regular Expression	Use Case
[0-9] or \d	Find all files/folders with at least one digit in its name.
a|b	Find all files/folders containing “a” or “b” in their name.
[^(A-Za-z)]	Find all files/folders containing at least one character in their name that is not in the range A-Z or a-z.
^E[0-9]{7}$	Find all files/folders which start with an “E” followed by exactly 7 digits.
[A-Za-z]:\\([^\\]+\\){2,4}[^\\]+$	Find all files/folders with a folder depth of at least 2 and at most 4.
[^\x00-\x7F]	Find all files/folders with invalid ASCII characters.
[^\P{C}]	Find all files/folders with Unicode characters which cannot be printed.
[\xA0]	Find all file/folder names that contain the non-breakable space character (Unicode NOBR, U+00A0) instead of a normal space character.
[~\""#%&\*\:<>\?\/\\{|}]	Find all file and folder names that contain characters which are invalid on SharePoint servers.
^\s+.*	Find all files and folders with a leading space.
\s+(\.[^.]+)$	Find files with an extension that have a trailing space at the end of their name.
.*\s+$	Find folders with a trailing space at the end of their name.

Tools for creating regular expressions

https://regex101.com/ (online)

http://regexpal.com/ (online)

http://sourceforge.net/projects/regexpeditor/ (download)

http://sourceforge.net/projects/regextester/ (download)

http://sourceforge.net/projects/regaxe/ (download)