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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