Other Enhancements
Key PHP 5.1.x features
Appendices
PHP Manual

# Migrating from PHP 5.0.x to PHP 5.1.x

## Table of Contents

- Key PHP 5.1.x features
- Changes in reference handling
- Reading []
- Integer values in function parameters
- Class and object changes
- Extensions
- Date/time support
- Changes in database support
- Checking for E_STRICT

See also the migration guides for PHP versions 5.0.x and 5.2.x.

Other Enhancements
Key PHP 5.1.x features
Appendices
PHP Manual