A couple of days ago, O’Reilly published a free mini eBook from Davey Shafik about Upgrading to PHP 7. This eBook has around 80 pages and is available in ePub, Mobi, and PDF at this link.

“Upgrading to PHP 7” book review:

PHP 7—the most dramatic update to the language in over a decade—has arrived. This O’Reilly report provides you with a short guide to the major changes in this new release, including a revamped engine (Zend Engine 3), a bunch of new features, and lots of language cleanup. You’ll learn about basic language changes, deprecated features, Unicode enhancements, changes in Object-Oriented programming, and other enhancements.

The book also covers why it took more than 10 years for the next major version of PHP since PHP 5 – and also what happened to version 6 in the meantime.

Important details regarding changes to PHP 7, include:

– Deprecated features, starting with alternative PHP tags and POSIX-compatible regular expressions

– Uniform Variable Syntax, including consistency fixes and new syntax

– Basic language changes, such as new operators, constant arrays, new functions, and regular expressions

– Expectations and Assertions

– Error handling

– Enhancements to PHP’s Unicode, closure, and Generator features

– Changes in Object-Oriented programming

– Scalar type hints (perhaps the most polarizing and exciting new feature)

– Quoted from daveyshafik.com