About regular expressions

Regular expressions are patterns that describe character combinations in text. Use them in your searches to help describe concepts such as "sentences that begin with `The'" and "attribute values that contain a number." The following table lists the special characters in regular expressions, their meanings, and usage examples.

To search for text containing one of the special characters in the table, escape the special character with a backslash. For example, to search for the asterisk in the phrase "some conditions apply*," your search pattern might look like this: apply\*. If you don't escape the asterisk, you'll find all the occurrences of "apply" (as well as any of "appl", "applyy", and "applyyy"), not just the ones followed by an asterisk.

Character	Matches	Example
^	Beginning of input or line.	`^T` matches "T" in "This good earth" but not in "Uncle Tom's Cabin"
$	End of input or line.	`h$` matches "h" in "teach" but not in "teacher"
*	The preceding character 0 or more times.	`um*` matches "um" in "rum", "umm" in "yummy", and "u" in "huge"
+	The preceding character 1 or more times.	`um+` matches "um" in "rum" and "umm" in "yummy", but matches nothing in "huge"
?	The preceding character 0 or 1 time.	`st?on` matches "son" in "Johnson" and "ston" in "Johnston" but nothing in "Appleton" or "tension"
.	Any single character except newline (line feed).	`.an` matches "ran" and "can" in the phrase "bran muffins can be tasty"
x\|y	Either x or y.	`FF0000\|0000FF` matches "FF0000" in `BGCOLOR="#FF0000"` and "0000FF'" in `FONT COLOR="#0000FF"`
{n}	Exactly n occurrences of the preceding character.	`o{2}` matches "oo" in "loom" and the first two o's in "mooooo", but matches nothing in "money"
{n,m}	At least n and at most m occurrences of the preceding character.	`F{2,4}` matches "FF" in "#FF0000" and the first four Fs in #FFFFFF
[abc]	Any one of the characters enclosed in the brackets. Specify a range of characters with a hyphen (for example, [a-f] is equivalent to [abcdef]).	`[e-g]` matches "e" in "bed", "f" in "folly", and "g" in "guard"
[^abc]	Any character not enclosed in the brackets. Specify a range of characters with a hyphen (for example, [^a-f] is equivalent to [^abcdef]).	`[^aeiou]` initially matches "r" in "orange", "b" in "book", and "k" in "eek!"
\b	A word boundary (such as a space or carriage return).	`\bb` matches "b" in "book" but nothing in "goober" or "snob"
\B	A non-word boundary.	`\Bb` matches "b" in "goober" but nothing in "book"
\d	Any digit character. Equivalent to [0-9].	`\d` matches "3" in "C3PO" and "2" in "apartment 2G"
\D	Any non-digit character. Equivalent to [^0-9].	`\D` matches "S" in "900S" and "Q" in "Q45"
\f	Form feed.
\n	Line feed.
\r	Carriage return.
\s	Any single whitespace character, including space, tab, form feed, or line feed.	`\sbook` matches "book" in "blue book" but nothing in "notebook"
\S	Any single non-whitespace character.	`\Sbook` matches "book" in "notebook" but nothing in "blue book"
\t	A tab.
\w	Any alphanumeric character, including underscore. Equivalent to [A-Za-z0-9_].	b\w* matches "barking" in "the barking dog" and both "big" and "black" in "the big black dog"
\W	Any non-alphanumeric character. Equivalent to [^A-Za-z0-9_].	\W matches "&" in "Jake & Mattie" and "%" in "100%"