regular expressions Definition
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® Prime software are the same as those used in many 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. |