Editing PHP (section)

=== PHP 7 ===
During 2014 and 2015, a new major PHP version was developed, PHP&nbsp;7. The numbering of this version involved some debate among internal developers.<ref>{{cite web|url=https://philsturgeon.uk/php/2014/07/23/neverending-muppet-debate-of-php-6-v-php-7/|title=The Neverending Muppet Debate of PHP&nbsp;6 v PHP&nbsp;7|access-date=2015-11-19|archive-url=https://web.archive.org/web/20151119132438/https://philsturgeon.uk/php/2014/07/23/neverending-muppet-debate-of-php-6-v-php-7/|archive-date=2015-11-19|url-status=dead}}</ref> While the PHP&nbsp;6 Unicode experiments had never been released, several articles and book titles referenced the PHP&nbsp;6 names, which might have caused confusion if a new release were to reuse the name.<ref>{{cite web |title=RFC: Name of Next Release of PHP |url=https://wiki.php.net/rfc/php6 |date=2014-07-07 |access-date=2014-07-15 |website=php.net}}</ref> After a vote, the name PHP&nbsp;7 was chosen.<ref>{{cite web|title=Re: [PHP-DEV] [VOTE] [RFC] Name of Next Release of PHP (again) |url=https://www.mail-archive.com/internals@lists.php.net/msg68598.html |date=2014-07-30 |access-date=2014-07-30}}</ref>

The foundation of PHP&nbsp;7 is a PHP [[branching (version control)|branch]] that was originally dubbed ''PHP next generation'' (''phpng''). It was authored by Dmitry Stogov, Xinchen Hui and Nikita Popov,<ref>{{cite web|url=http://news.php.net/php.internals/73888|title=phpng: Refactored PHP Engine with Big Performance Improvement|website=news.php.net}}</ref> and aimed to optimize PHP performance by refactoring the Zend Engine while retaining near-complete language compatibility.<ref>{{cite web |url=https://wiki.php.net/rfc/phpng |title=PHP: rfc:phpng |access-date=16 December 2014 |website=php.net}}</ref> By 14 July 2014, [[WordPress]]-based benchmarks, which served as the main benchmark suite for the phpng project, showed an almost 100% increase in performance. Changes from phpng make it easier to improve performance in future versions, as more compact data structures and other changes are seen as better suited for a successful migration to a [[Just-in-time compilation|just-in-time]] (JIT) compiler.<ref name="php.net-7">{{cite web|url=https://wiki.php.net/phpng |title=PHP: phpng |website=php.net |access-date=2014-07-15}}</ref> Because of the significant changes, the reworked Zend Engine was called ''Zend Engine 3'', succeeding Zend Engine 2 used in PHP&nbsp;5.<ref name="github.com-2014">{{cite web |url=https://github.com/php/php-src/commit/150dc69d6eee35738f505e925ee664c02060196d |website=github.com |date=2014-12-05 |access-date=2014-12-05 |title=Merge branch 'ZendEngine3'}}</ref>

Because of the major internal changes in phpng, it must receive a new [[Software versioning|major version]] number of PHP, rather than a minor PHP&nbsp;5 release, according to PHP's release process.<ref name="PHP-2011" /> Major versions of PHP are allowed to break backward-compatibility of code and therefore PHP&nbsp;7 presented an opportunity for other improvements beyond phpng that require backward-compatibility breaks.{{Citation needed|date=April 2024}} In particular, it involved the following changes:
* Many fatal or recoverable-level legacy PHP error mechanisms were replaced with modern object-oriented [[Exception (computer science)|exceptions]].<ref name="php.net" />
* The syntax for variable dereferencing was reworked to be internally more consistent and complete, allowing the use of the operators <code>-></code>, <code>[]</code>, <code>()</code>,<code>{}</code>, and <code>::</code>, with arbitrary meaningful left-side expressions.<ref name="php.net-2014b">{{cite web |url=https://wiki.php.net/rfc/uniform_variable_syntax |title=PHP RFC: Uniform Variable Syntax |date=2014-05-31 |access-date=2014-07-30 |website=php.net}}</ref>
* Support for legacy PHP&nbsp;4-style constructor methods was deprecated.<ref>{{Cite web|url=https://3v4l.org/udRhX|title=Online PHP editor &#124; output for udRhX|website=3v4l.org}}</ref>
* The behavior of the [[foreach loop|<code>foreach</code> statement]] was changed to be more predictable.<ref>{{cite web|url=https://wiki.php.net/rfc/php7_foreach|title=PHP RFC: Fix "foreach" behavior|access-date=2015-05-21|website=php.net}}</ref>
* Constructors for the few classes built-in to PHP which returned null upon failure were changed to throw an exception instead, for consistency.<ref>{{cite web|url=https://wiki.php.net/rfc/internal_constructor_behaviour|title=PHP RFC: Constructor behaviour of internal classes|access-date=2015-05-21|website=php.net}}</ref>
* Several unmaintained or deprecated [[server application programming interface]]s (SAPIs) and extensions were removed from the PHP core, most notably the legacy <code>mysql</code> extension.<ref>{{cite web|url=https://wiki.php.net/rfc/removal_of_dead_sapis_and_exts|title=PHP RFC: Removal of dead or not yet PHP7 ported SAPIs and extensions|access-date=2015-05-21|website=php.net}}</ref>
* The behavior of the <code>list()</code> operator was changed to remove support for strings.<ref>{{cite web|url=https://wiki.php.net/rfc/fix_list_behavior_inconsistency|title=PHP RFC: Fix list() behavior inconsistency|access-date=2015-05-21|website=php.net}}</ref>
* Support was removed for legacy ASP-style delimiters <code>&lt;%</code> and <code>%&gt;</code> and <code>&lt;script language="php"&gt; ... &lt;/script&gt;</code>.<ref>{{cite web|url=https://wiki.php.net/rfc/remove_alternative_php_tags|title=PHP RFC: Remove alternative PHP tags|access-date=2015-05-21|website=php.net}}</ref>
* An oversight allowing a [[switch statement]] to have multiple <code>default</code> clauses was fixed.<ref>{{cite web|url=https://wiki.php.net/rfc/switch.default.multiple|title=PHP RFC: Make defining multiple default cases in a switch a syntax error|access-date=2015-05-21|website=php.net}}</ref>
* Support for hexadecimal number support in some implicit conversions from strings to number types was removed.<ref>{{cite web|url=https://wiki.php.net/rfc/remove_hex_support_in_numeric_strings|title=PHP RFC: Remove hex support in numeric strings|access-date=2015-05-21|website=php.net}}</ref>
* The [[left-shift operator|left-shift]] and [[right-shift operator|right-shift]] operators were changed to behave more consistently across platforms.<ref name="php.net-5" />
* Conversions between floating-point numbers and integers were changed (e.g. infinity changed to convert to zero) and implemented more consistently across platforms.<ref name="php.net-5">{{cite web|url=https://wiki.php.net/rfc/integer_semantics|title=PHP RFC: Integer Semantics|access-date=2015-05-21|quote=Making NaN and Infinity always become zero when cast to integer means more cross-platform consistency, and is also less surprising than what is currently produces|website=php.net}}</ref><ref>{{cite web|url=https://wiki.php.net/rfc/zpp_fail_on_overflow|title=PHP RFC: ZPP Failure on Overflow|access-date=2015-05-21|website=php.net}}</ref>

PHP&nbsp;7 also included new language features. Most notably, it introduced return type declarations for functions<ref name="php.net-2015a">{{cite web |url=https://wiki.php.net/rfc/return_types |title=RFC: Return Types |date=2015-01-27 |access-date=2015-01-28 |website=php.net}}</ref> which complement the existing parameter type declarations, and support for the [[Variable (computer science)|scalar]] types (integer, float, string, and boolean) in parameter and return type declarations.<ref name="php.net-2015b">{{cite web|url=https://wiki.php.net/rfc/scalar_type_hints_v5|title=RFC: Scalar Type Declarations |date=2015-03-16 |access-date=2015-03-17 |website=php.net}}</ref>