regex101: PCRE2 (PHP >=7.3)

Regular Expression

^(?:(?:25[0-5]|(?:2[0-4]|1\d|[1-9]|)\d)\.?\b){4}$

New

Purpose:
This is supposed to be a learning process. The first 1-9 tasks are supposed to be done with using "standard" regex, ie, teach the user to use \s, \w, \d, aswell as backrefs and similar basic things.
Later down the road, at task 10-13 we start introducing them to lookarounds. These are fairly basic for now.
At task 14-15 we show them the true power of lookarounds and encourage them to use them properly and what can truly be done with them.
Task 16 and forward is supposed to introduce \G and other nifty ideas. This is where its supposed to be more advanced and trickier.


Task order:
	1: Word Boundaries
	2: Capitalize i
	3: Uppercase Consonants
	4: Retreive Numbers
	5: Whitespaces
	6: Broken Keyboard
	7: Validate an IP
	8: Html Tags
	9: Validate floating numbers
	10: Followed by #
	11: Spam filter
	12: Match an E-Mail (Simplified)
	13: Not surrounded by digits
	14: Repeated words
	15: start before end
	16: Every other digit
	17: The thousands
	18: Quoted text with escapes
	19: R