Difference between PHP 5.3 to PHP 7.x

Question

My project is running on PHP 5.3. Now I want to upgrade PHP to a higher version as 7.x.

Before the update I tried to search difference and complexity but couldn't get a satisfactory answer.

Searched links:

1. Updraft article
2. PHP manual

I also want to know that is there need to change my code which is currently running correctly on PHP 5.3?

Any suggestions would be appreciated.

Answer 1

1. The Name’s PHP 7 (Not 6)

The current stable release uses the version number PHP 5.6. After some disputethe development team decided they would omit the PHP 6 name for the next major release. PHP 6 already existed in the past as an experimental project but never reached the production phase.

2. The Brand Spanking New Zend Engine

The Zend engine has been powering PHP since 1999 when it was introduced with the then new PHP 4 release. Zend – not to confused with the Zend Framework – is an open-source execution engine written in C that interprets the PHP language. The current PHP 5.X series use Zend Engine II that enhanced the funtionality of the initial engine and adds an extensible object model and a significant performance enhancement to the language.

PHP 7 receives a brand new version of the engine coming under the code name of PHP#NG (Next Generation).

3. Twice The Speed

The most easily recognizable advantage of the new PHPNG engine is the significant performance improvement. The development team of PHPNG refactored the Zend Engine, and remarkably optimized memory usage.

The results? You can see the performance benchmarks provided by the Zend Performance Team below. By using PHP 7 not only your code will be executed faster but you will also need fewer servers to serve the same amount of users.

4. Facilitates Error Handling

To say the least, handling fatal and catchable fatal errors have never been an easy task for PHP coders. The new Engine Exceptions will allow you to replace these kind of errors with exceptions. If the exception is not caught, PHP will continue to return the same fatal errors as it does in the current 5.X series.

The new \EngineException objects don’t extend the \Exception Base Class. This ensures backward compatibility and results in two different kinds of exceptions in error handling: traditional and engine exceptions.

To enable programmers to catch both, PHP 7 introduces a new shared Parent Class under the name of \BaseException.

5. 64-Bit Windows Systems Support

PHP is a prominent member of the LAMP stack which means its native environment is Linux – but it’s also possible to run it on a Windows system. The 5.X series don’t yet provide 64-bit integer or large file support, so until now x64 builds have been considered experimental.

PHP 7 will change this as it introduces consistent 64-bit support which means both native 64-bit integers and large files will be supported, allowing you to confidently run the language on your 64-bit Windows system in the future.

6. New Spaceship and Null Coalescing Operators

The Spaceship operator runs under the official name of Combined Comparison Operator. The notation of the new operator looks like this: <=> (kind of like a simplified spaceship, if you imagine it right).

The spacehip operator returns 0 if both operands are equal, 1 if the left is greater, and -1 if the right is greater. It’s also called a three-way comparison operator, and it already exists in other popular programming languages like Perl and Ruby.

Have you ever wanted to prevent unintended return values by declaring the return type of a function? Well, the new PHP 7 enables developers to enhance the quality of their code with the help of return type declarations.

The image below depicts a very simple use case where the foo() function is supposed to return an array. Check out more complicated examples here

For more details: Read more

Answer 2

You can find change logs for the individual major PHP releases on php.net, including migration guides (e.g. http://php.net/manual/en/migration54.php).

With regards to backwards compatibility, check out the following link: http://php.net/manual/en/migration70.incompatible.php