PHP Versions

This section is not intended to review the history of PHP, but rather, aims to make a brief review of the main features and changes that the language from version 3 to 5.

PHP had versions before 3, but this was chosen as a starting point because it is the oldest version that can be seen today in some places.

This happens, mainly, because the sites in question - that were developed in origin when this version was the last one - meet a precise objective and has not needed updating to later versions.

Today, most applications are scheduled with version 4, although they are constantly migrating to version 5.

PHP 3

PHP version 3 was created in 1997 and is considered a continuation of an earlier version of PHP called PHP / FI 2.0, although calling it "continuation" is relative because the code was completely rewritten, and only its way of working and some functions were maintained implemented: the idea was to keep the users of PHP / FI and continue working in conjunction with them.

In this version, PHP had characteristics that lasted over time and even today are a strong point of the language: support for a large number of databases, interaction with network protocols and use of extensions.

In terms of object orientation (POO), version 3 supports medium, without implementing all the possibilities of this paradigm.

It was already glimpsed at this time to a large number of people (tens of thousands of users and hundreds of thousands of websites) who were interested not only in using but in collaborating with the language. PHP 3.0 was officially launched in the month of June 1998.

PHP 4

Taking the previous version as a point of reference, the kernel (part of the program that is responsible for managing the processes) of PHP was rewritten for version 4. This occurred because, as it became more and more popular, the existing applications in the market were becoming more complex and requiring faster execution speed than PHP 3.0 could offer.

The new core was called Zend Engine (referring to the names of its main developers, Zeev Zuraski and Andi Gutmans)

Other important improvements are: the support for most web servers, the functions for the handling of HTTP sessions, the output buffers and the inclusion of a large number of functions of different purposes.

Version 4 was installed in more than 20% of Internet domains. As for the POO, the support that PHP offered, practically, was not modified in relation to version 3. What was modified was its use, since it became common for a large number of users, generally, in applications Large size. This requirement almost explicit by users would have its response to version 5. A similar case was given with XML: PHP gave support to handle this kind of files but was quite limited in terms of the options offered. An important point is that the extensions written for PHP 3 did not work with PHP 4 (although it is possible to port extensions to PHP 4) if you have access to the original sources).

PHP 4 was first introduced to the market in 1999 and the official version was launched in May 2000.

PHP 5

The changes that PHP undergoes in this version are truly important, and it could be said that they revolutionized the language.

The first version of PHP 5 was released in June 2003. Among the new features included, we can highlight:

• Improvements on the Zend engine (Zend Engine II)
• In terms of object-oriented programming, PHP now offers notable improvements that make it a fully competent alternative in this respect compared to other languages with a history in this field
• Improvements in XML support (the code was rewritten compared to the previous version)
• Exceptions handling (similar to how Java does it)
• Inclusion of support for SQLite