Regular Expressions: Difference between revisions

Latest revision as of 18:15, 20 December 2019

Regular expressions are used for matching text.
You can test regular expressions online at [1].

[a-zA-Z]

You should match numbers using [0-9].
\d will match unicode characters which are classified as digits.
See \d vs 0-9

Mostly copied from Regex DB.

Without matching scientific notation (e.g. 1.5e-6). Reference

[-+]?[0-9]*\.?[0-9]+

With matching scientific notation (e.g. 1.5e-6). Reference
Capturing significand and exponent separately.

([-+]?[0-9]*\.?[0-9]+)(?:[eE]([-+]?[0-9]+))?

Capturing the entire string together.

([-+]?[0-9]*\.?[0-9]+(?:[eE][-+]?[0-9]+)?)

@@ Line 1: / Line 1: @@
-Regular expressions are used for matching text.
+Regular expressions are used for matching text.<br>
+You can test regular expressions online at [https://regex101.com/].
+==Syntax==
+===Letters===
+<code>[a-zA-Z]</code>
+===Numbers===
+You should match numbers using <code>[0-9]</code>.<br>
+<code>\d</code> will match unicode characters which are classified as digits.<br>
+See [https://stackoverflow.com/questions/890686/should-i-use-d-or-0-9-to-match-digits-in-a-perl-regex \d vs 0-9]
 ==Useful Regular Expressions==
+Mostly copied from [https://rgxdb.com/ Regex DB].
 ===Floating Point Number===
+Without matching scientific notation (e.g. 1.5e-6).
 [https://www.regular-expressions.info/floatingpoint.html Reference]
 <syntaxhighlight lang="ragel">
 [-+]?[0-9]*\.?[0-9]+
+</syntaxhighlight>
+With matching scientific notation (e.g. 1.5e-6).
+[https://rgxdb.com/r/1RSPF8MG Reference]<br>
+Capturing significand and exponent separately.
+<syntaxhighlight lang="ragel">
+([-+]?[0-9]*\.?[0-9]+)(?:[eE]([-+]?[0-9]+))?
+</syntaxhighlight>
+Capturing the entire string together.
+<syntaxhighlight lang="ragel">
+([-+]?[0-9]*\.?[0-9]+(?:[eE][-+]?[0-9]+)?)
 </syntaxhighlight>