The following are some useful regular expressions that I’ve developed over time. These expressions assume that the string you are trying to match is complete. Happy parsing!

Non-alphanumeric

Matches non-alphanumeric characters.

([^a-zA-Z\d])+

Time

Matches valid time strings in the format HH:MM.

(([0-1][0-9])|(2[0-3])):([0-5][0-9])

Phone

Matches phone numbers in the format (XXX) XXX-XXXX.

\([0-9][0-9][0-9]\) [0-9][0-9][0-9]\-[0-9][0-9][0-9][0-9]

Zip Code

Matches zip codes in the format XXXXX or XXXXX-XXXX.

([0-9][0-9][0-9][0-9][0-9]\-[0-9][0-9][0-9][0-9])|([0-9][0-9][0-9][0-9][0-9])

Comments

Matches multi-line comment strings which use /* and */ as separators, such as in Java.

^(/\*)(.*)(\*/)

Number Phrase

Matches numbers which are spelled out in words from zero to ninety-nine.

((one)|(two)|(three)|(four)|(five)|(six)|(seven)|(eight)|(nine)|(ten)|(twenty)|(thirty)|(forty)|(fifty)|(sixty)|(seventy)|(eighty)|(ninety))(\-((one)|(two)|(three)|(four)|(five)|(six)|(seven)|(eight)|(nine))){0,1}

Roman Numerals

Matches only Roman numerals from 0 to 39.

(X{1,3})(I[XV]|V?I{0,3})|(I[XV]|V?I{1,3})|V

Date

Matches date strings in the format of YYYY-MM-DD with support for leap years. I’ve written a guide on how this expression was derived here.

(([0-9][0-9]((0[48])|([2468][048])|([13579][26])))(-)(((02)(-)((0[1-9])|([1-2][0-9])))|(((0[469])|11)(-)((0[1-9])|([1-2][0-9])|(30)))|(((0[13578])|1[02])(-)((0[1-9])|([1-2][0-9])|(3[0-1])))))|(([0-9][0-9]((0[1235679])|([2468][1235679])|([13579][1345789])))(-)(((02)(-)((0[1-9])|([1-2][0-8])))|(((0[469])|11)(-)((0[1-9])|([1-2][0-9])|(30)))|(((0[13578])|1[02])(-)((0[1-9])|([1-2][0-9])|(3[0-1])))))

Even Parity

Matches numbers which have even parity (numbers whose digits add up to an even number).

(([02468]*[13579]){2})*[02468]+