Regular Expression

Learn to use regular expressions by following RegexTip. From @JohnDCook.

[Regular Expression @RegexTip]

Four tips for learning regular expressions https://t.co/8SfGbvM1LZ

[Regular Expression @RegexTip]

Flatten JSON files so they're easier to grep: https://t.co/CGJjn9D1gI

[Regular Expression @RegexTip]

Graphemes https://t.co/AEkUB6C6AB

[Regular Expression @RegexTip]

To group without capturing, use (?: ... ).

[Regular Expression @RegexTip]

“Regular expressions aren’t random jumbles of punctuation—they’re carefully thought-out jumbles of punctuation!” -- The Perl Cookbook

[Regular Expression @RegexTip]

\> represents an ending word boundary and match a position between two tokens. Some engines don't support this.

[Regular Expression @RegexTip]

\< represents a beginning word boundary and match a position between two tokens. Some engines don't support this.

[Regular Expression @RegexTip]

Awk regular expressions https://t.co/47Hj0yVTb9

[Regular Expression @RegexTip]

\b matches a word boundary; \B matches anything but a word boundary.

[Regular Expression @RegexTip]

Don't confuse \1 with $1. \1 is used inside a regex; $1 (in Perl) is used outside the regex after a match.

[Regular Expression @RegexTip]

Many languages support Perl 5 regular expressions. For example, Microsoft .NET supports Perl 5 regex with some of its own extensions.

[Regular Expression @RegexTip]

\d represents the numerical characters, or [0123456789]. Its complement is \D.

[Regular Expression @RegexTip]

Using regular expressions in PowerShell https://t.co/Ly5CzsTc0N

[Regular Expression @RegexTip]

If you're going to work with regular expressions, it's worthwhile to learn Perl notation even if you don't intend to ever use Perl.

[Regular Expression @RegexTip]

You can include comments inside a regex with (?# ... ). For example, /the\s+(?# One or more spaces)end

[Regular Expression @RegexTip]

[a-z] matches all lower case letters. [-az] matches '-', 'a', or 'z'.

[Regular Expression @RegexTip]

Perl stores the content of the previous match in $&, the text to the left of the match in $`, and the text to the right in $'.

[Regular Expression @RegexTip]

Grep rewritten in Perl (and so it supports Perl regular expressions) https://t.co/qCZWYFaOk8

[Regular Expression @RegexTip]

Regular expressions in Rust https://t.co/H5ckumA2Di

[Regular Expression @RegexTip]

The greatest regex trick ever https://t.co/geQ79RIN1H

[Regular Expression @RegexTip]

If a dash is the first or last character in a character class, it is a literal dash and does not indicate a range.