PHP Manual
Function Reference
Text Processing
PCRE
PCRE Patterns
PCRE regex syntax
Possible modifiers in regex patterns
Differences From Perl
PCRE Patterns
Introduction
PCRE Patterns
PHP Manual
Pattern Syntax
Table of Contents
Introduction
Delimiters
Meta-characters
Escape sequences
Unicode character properties
Anchors
Dot
Character classes
Alternation
Internal option setting
Subpatterns
Repetition
Back references
Assertions
Once-only subpatterns
Conditional subpatterns
Comments
Recursive patterns
Performance