PCRE Character Classes
PHP uses PCRE (Perl Compatible Regular Expressions). PCRE offers richer character classes than basic regex, including POSIX classes and Unicode properties.
PHP
Intermediate
5 min read
PCRE Character Classes
Example
<?php
// Shorthand classes
"/\d/" // Digit [0-9]
"/\D/" // Non-digit
"/\w/" // Word char [A-Za-z0-9_]
"/\s/" // Whitespace
"/\S/" // Non-whitespace
// POSIX classes (use inside character class)
"/[[:alpha:]]/" // Letters
"/[[:digit:]]/" // Digits
"/[[:alnum:]]/" // Alphanumeric
"/[[:space:]]/" // Whitespace
"/[[:punct:]]/" // Punctuation
// Unicode categories (with u flag)
"/\p{L}/u" // Unicode letters
"/\p{N}/u" // Unicode numbers
"/\p{Z}/u" // Unicode separators (spaces) Pro Tip
Use the /u modifier for patterns on UTF-8 strings — without it, multibyte characters may be mishandled.