Differences from POSIX regex
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
Performances
Differences from POSIX regex
Introduction
PCRE Patterns
PHP Manual