Regular Expression Quick Reference

Numbers

^-?\d+$

A signed integer with no leading plus.

^\d{1,3}(,\d{3})*$

Digits grouped in thousands with commas.

^0[xX][0-9a-fA-F]+$

A hexadecimal literal.

Text

^\s+|\s+$

Leading and trailing whitespace, for trimming.

(\b\w+\b)\s+\1

A word repeated twice in a row.

^[A-Z][a-z]+(?: [A-Z][a-z]+)*$

Capitalised words separated by single spaces.

Structured values

^\d{4}-\d{2}-\d{2}$

A calendar date in ISO 8601 form.

^([0-9]{1,3}\.){3}[0-9]{1,3}$

Four dotted decimal octets, range not checked.

^#(?:[0-9a-f]{3}|[0-9a-f]{6})$

A three or six digit colour literal.