This article was originally published on programmingliftoff.com as Learn Regular Expressions using Atom.
This is a short little post with the goal of helping you to learn the elusive regular expressions!
This takes advantage of a built in regex feature in the Atom text editor. It may work in other text editors as well, so give it a try in your favorite text editor or IDE. If it doesn't work, you can download Atom here (don't worry, its free!).
Tutorial
First, create a new file in the Atom editor.
Next, type in a line of text. Here is the line I will be using (Hello). [World!]
.
Next type CMD+f (Ctrl+f on Windows) to open the find and replace utility.
Then select the 'regex' option to treat the search item as a regular expression (see red arrow below).
Finally, highlight the line of text that you typed and press CMD+f (Ctrl+f on Windows). The search box should update to display your selection formatted as a regular expression.
Congratulations! You now know how to use Atom to build regular expressions for you!
Understanding the generated expression
Recall that the original string was (Hello). [World!]
. Parenthesis and brackets are special symbols in regex, so they must be escaped with the \
character. Note that a period .
is also a special regex character. This is one of the most misused characters in regex, because a period by itself will match any character! Simply typing a .
to match a period in a string will match that string, but it will also match any string that contains any other character in place of the period.
Limitations
This only works for one-line expressions. :(Â Even magic has its limits :).
Additional links
https://regexone.com/ - An awesome interactive tutorial for learning regular expressions.
https://regex101.com/ - A regex tester. You must know the regular expression, or try typing regular expressions until they match the example text you entered.
Mastering Regular Expressions - Great book to learn how to write regular expressions. (This is an affiliate link.)
Top comments (2)
Hi, other online regex tester: extendsclass.com/regex-tester.html
No mention to debuggex.com ???