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Glossary

regular expressions


Regular expressions are combinations of special character operators, which are symbols that control the search, that you can use to construct search strings for advanced find and/or replace searches.

The regular expressions used to perform searches in the Quartus® II software are the same as those used in many UNIX and Linux applications. For more information about regular expressions, see Jeffrey E.F. Friedl's Mastering Regular Expressions (Sebastopol: O'Reilly & Associates, Inc., 1997).

The table below shows examples of regular expression metacharacters, their descriptions, and their applications:

Operator Description Example
. (dot) Matches any single character of the input line. .op finds top and hop, and it also finds the substring, top, in stop.
^ This metacharacter does not match any character but represents the beginning of the input line. ^A finds the letter A at the beginning of a line.
? Matches a string of zero or one character that would match the character to the immediate left of ?. m?y finds the substring y in the words, by and gray, and it also finds the entire word, my.
$ This metacharacter does not match any character but represents the end of an input line. end$ finds end when it is the last string on a line.
\ This metacharacter is used to turn off the special meaning of metacharacters. \. finds only the . (dot) character. \? finds only the ? character.
[...] Matches one or more characters or a range of characters in the set. [a-c]at finds bat and cat, but not sat.
[^...] Matches one or more characters or a range of characters not in the set. [^a-c]at finds sat and rat, but not bat or cat.
+ Matches a string of one or more characters that would match the character to the immediate left of +. m+e finds me, but not made, mine, or more.
* Matches a string of zero or more characters that would match the character to the immediate left of *. m*y finds the substring y in the words, by and gray, and it also finds the entire word, my, as well as the substring, mmy, in the word, mummy.

 

The table below shows how to construct a regular expression search for special characters:

To find: Use the regular expression:
newline characters \n
tabs \t
.(dot), *, ?, ^, and other metacharacters used in regular expression searches \., \*, \?, \^, and so on.


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- Last Modified: 01/05/2003 11:57:00 -

 

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