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<div class="home"><a href="index.html">PHP Manual</a></div>
</div><hr /><div id="migration71.new-features" class="sect1">
<h2 class="title">New features</h2>
<div class="sect2" id="migration71.new-features.nullable-types">
<h3 class="title">Nullable types</h3>
<p class="para">
Type declarations for parameters and return values can now be marked as
nullable by prefixing the type name with a question mark. This signifies
that as well as the specified type, <strong><code>NULL</code></strong> can be passed as an argument, or
returned as a value, respectively.
</p>
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /><br /></span><span style="color: #007700">function </span><span style="color: #0000BB">testReturn</span><span style="color: #007700">(): ?</span><span style="color: #0000BB">string<br /></span><span style="color: #007700">{<br /> return </span><span style="color: #DD0000">'elePHPant'</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">testReturn</span><span style="color: #007700">());<br /><br />function </span><span style="color: #0000BB">testReturn</span><span style="color: #007700">(): ?</span><span style="color: #0000BB">string<br /></span><span style="color: #007700">{<br /> return </span><span style="color: #0000BB">null</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">testReturn</span><span style="color: #007700">());<br /><br />function </span><span style="color: #0000BB">test</span><span style="color: #007700">(?</span><span style="color: #0000BB">string $name</span><span style="color: #007700">)<br />{<br /> </span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$name</span><span style="color: #007700">);<br />}<br /><br /></span><span style="color: #0000BB">test</span><span style="color: #007700">(</span><span style="color: #DD0000">'elePHPant'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">test</span><span style="color: #007700">(</span><span style="color: #0000BB">null</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">test</span><span style="color: #007700">();</span>
</span>
</code></div>
</div>
<p class="para">The above example will output:</p>
<div class="example-contents screen">
<div class="cdata"><pre>
string(10) "elePHPant"
NULL
string(10) "elePHPant"
NULL
Uncaught Error: Too few arguments to function test(), 0 passed in...
</pre></div>
</div>
</div>
</div>
<div class="sect2" id="migration71.new-features.void-functions">
<h3 class="title">Void functions</h3>
<p class="para">
A <span class="type"><span class="type void">void</span></span> return type has been introduced. Functions declared with
void as their return type must either omit their return statement altogether,
or use an empty return statement. <strong><code>NULL</code></strong> is not a valid return value for a
void function.
</p>
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">function </span><span style="color: #0000BB">swap</span><span style="color: #007700">(&</span><span style="color: #0000BB">$left</span><span style="color: #007700">, &</span><span style="color: #0000BB">$right</span><span style="color: #007700">): </span><span style="color: #0000BB">void<br /></span><span style="color: #007700">{<br /> if (</span><span style="color: #0000BB">$left </span><span style="color: #007700">=== </span><span style="color: #0000BB">$right</span><span style="color: #007700">) {<br /> return;<br /> }<br /><br /> </span><span style="color: #0000BB">$tmp </span><span style="color: #007700">= </span><span style="color: #0000BB">$left</span><span style="color: #007700">;<br /> </span><span style="color: #0000BB">$left </span><span style="color: #007700">= </span><span style="color: #0000BB">$right</span><span style="color: #007700">;<br /> </span><span style="color: #0000BB">$right </span><span style="color: #007700">= </span><span style="color: #0000BB">$tmp</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #0000BB">$a </span><span style="color: #007700">= </span><span style="color: #0000BB">1</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$b </span><span style="color: #007700">= </span><span style="color: #0000BB">2</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">swap</span><span style="color: #007700">(</span><span style="color: #0000BB">$a</span><span style="color: #007700">, </span><span style="color: #0000BB">$b</span><span style="color: #007700">), </span><span style="color: #0000BB">$a</span><span style="color: #007700">, </span><span style="color: #0000BB">$b</span><span style="color: #007700">);</span>
</span>
</code></div>
</div>
<p class="para">The above example will output:</p>
<div class="example-contents screen">
<div class="cdata"><pre>
null
int(2)
int(1)
</pre></div>
</div>
</div>
<p class="para">
Attempting to use a void function's return value simply evaluates to
<strong><code>NULL</code></strong>, with no warnings emitted. The reason for this is because warnings
would implicate the use of generic higher order functions.
</p>
</div>
<div class="sect2" id="migration71.new-features.symmetric-array-destructuring">
<h3 class="title">Symmetric array destructuring</h3>
<p class="para">
The shorthand array syntax (<em>[]</em>) may now be used to
destructure arrays for assignments (including within
<em>foreach</em>), as an alternative to the existing
<span class="function"><a href="function.list.html" class="function">list()</a></span> syntax, which is still supported.
</p>
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$data </span><span style="color: #007700">= [<br /> [</span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #DD0000">'Tom'</span><span style="color: #007700">],<br /> [</span><span style="color: #0000BB">2</span><span style="color: #007700">, </span><span style="color: #DD0000">'Fred'</span><span style="color: #007700">],<br />];<br /><br /></span><span style="color: #FF8000">// list() style<br /></span><span style="color: #007700">list(</span><span style="color: #0000BB">$id1</span><span style="color: #007700">, </span><span style="color: #0000BB">$name1</span><span style="color: #007700">) = </span><span style="color: #0000BB">$data</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">];<br /><br /></span><span style="color: #FF8000">// [] style<br /></span><span style="color: #007700">[</span><span style="color: #0000BB">$id1</span><span style="color: #007700">, </span><span style="color: #0000BB">$name1</span><span style="color: #007700">] = </span><span style="color: #0000BB">$data</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">];<br /><br /></span><span style="color: #FF8000">// list() style<br /></span><span style="color: #007700">foreach (</span><span style="color: #0000BB">$data </span><span style="color: #007700">as list(</span><span style="color: #0000BB">$id</span><span style="color: #007700">, </span><span style="color: #0000BB">$name</span><span style="color: #007700">)) {<br /> </span><span style="color: #FF8000">// logic here with $id and $name<br /></span><span style="color: #007700">}<br /><br /></span><span style="color: #FF8000">// [] style<br /></span><span style="color: #007700">foreach (</span><span style="color: #0000BB">$data </span><span style="color: #007700">as [</span><span style="color: #0000BB">$id</span><span style="color: #007700">, </span><span style="color: #0000BB">$name</span><span style="color: #007700">]) {<br /> </span><span style="color: #FF8000">// logic here with $id and $name<br /></span><span style="color: #007700">}</span>
</span>
</code></div>
</div>
</div>
</div>
<div class="sect2" id="migration71.new-features.class-constant-visibility">
<h3 class="title">Class constant visibility</h3>
<p class="para">
Support for specifying the visibility of class constants has been added.
</p>
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">class </span><span style="color: #0000BB">ConstDemo<br /></span><span style="color: #007700">{<br /> const </span><span style="color: #0000BB">PUBLIC_CONST_A </span><span style="color: #007700">= </span><span style="color: #0000BB">1</span><span style="color: #007700">;<br /> public const </span><span style="color: #0000BB">PUBLIC_CONST_B </span><span style="color: #007700">= </span><span style="color: #0000BB">2</span><span style="color: #007700">;<br /> protected const </span><span style="color: #0000BB">PROTECTED_CONST </span><span style="color: #007700">= </span><span style="color: #0000BB">3</span><span style="color: #007700">;<br /> private const </span><span style="color: #0000BB">PRIVATE_CONST </span><span style="color: #007700">= </span><span style="color: #0000BB">4</span><span style="color: #007700">;<br />}</span>
</span>
</code></div>
</div>
</div>
</div>
<div class="sect2" id="migration71.new-features.iterable-pseudo-type">
<h3 class="title"><span class="type"><span class="type iterable">iterable</span></span> pseudo-type</h3>
<p class="para">
A new pseudo-type (similar to <span class="type"><a href="language.types.callable.html" class="type callable">callable</a></span>) called
<span class="type"><span class="type iterable">iterable</span></span> has been introduced. It may be used in parameter
and return types, where it accepts either arrays or objects that implement
the <a href="class.traversable.html" class="classname">Traversable</a> interface. With respect to subtyping,
parameter types of child classes may broaden a parent's declaration of <span class="type"><a href="language.types.array.html" class="type array">array</a></span>
or <a href="class.traversable.html" class="classname">Traversable</a> to <span class="type"><span class="type iterable">iterable</span></span>. With return types,
child classes may narrow a parent's return type of <span class="type"><span class="type iterable">iterable</span></span> to
<span class="type"><a href="language.types.array.html" class="type array">array</a></span> or an object that implements <a href="class.traversable.html" class="classname">Traversable</a>.
</p>
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">function </span><span style="color: #0000BB">iterator</span><span style="color: #007700">(</span><span style="color: #0000BB">iterable $iter</span><span style="color: #007700">)<br />{<br /> foreach (</span><span style="color: #0000BB">$iter </span><span style="color: #007700">as </span><span style="color: #0000BB">$val</span><span style="color: #007700">) {<br /> </span><span style="color: #FF8000">//<br /> </span><span style="color: #007700">}<br />}</span>
</span>
</code></div>
</div>
</div>
</div>
<div class="sect2" id="migration71.new-features.mulit-catch-exception-handling">
<h3 class="title">Multi catch exception handling</h3>
<p class="para">
Multiple exceptions per catch block may now be specified using the pipe
character (<em>|</em>). This is useful for when different
exceptions from different class hierarchies are handled the same.
</p>
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">try {<br /> </span><span style="color: #FF8000">// some code<br /></span><span style="color: #007700">} catch (</span><span style="color: #0000BB">FirstException </span><span style="color: #007700">| </span><span style="color: #0000BB">SecondException $e</span><span style="color: #007700">) {<br /> </span><span style="color: #FF8000">// handle first and second exceptions<br /></span><span style="color: #007700">}</span>
</span>
</code></div>
</div>
</div>
</div>
<div class="sect2" id="migration71.new-features.support-for-keys-in-list">
<h3 class="title">Support for keys in <span class="function"><a href="function.list.html" class="function">list()</a></span></h3>
<p class="para">
You can now specify keys in <span class="function"><a href="function.list.html" class="function">list()</a></span>, or its new shorthand
<em>[]</em> syntax. This enables destructuring of arrays with
non-integer or non-sequential keys.
</p>
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$data </span><span style="color: #007700">= [<br /> [</span><span style="color: #DD0000">"id" </span><span style="color: #007700">=> </span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #DD0000">"name" </span><span style="color: #007700">=> </span><span style="color: #DD0000">'Tom'</span><span style="color: #007700">],<br /> [</span><span style="color: #DD0000">"id" </span><span style="color: #007700">=> </span><span style="color: #0000BB">2</span><span style="color: #007700">, </span><span style="color: #DD0000">"name" </span><span style="color: #007700">=> </span><span style="color: #DD0000">'Fred'</span><span style="color: #007700">],<br />];<br /><br /></span><span style="color: #FF8000">// list() style<br /></span><span style="color: #007700">list(</span><span style="color: #DD0000">"id" </span><span style="color: #007700">=> </span><span style="color: #0000BB">$id1</span><span style="color: #007700">, </span><span style="color: #DD0000">"name" </span><span style="color: #007700">=> </span><span style="color: #0000BB">$name1</span><span style="color: #007700">) = </span><span style="color: #0000BB">$data</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">];<br /><br /></span><span style="color: #FF8000">// [] style<br /></span><span style="color: #007700">[</span><span style="color: #DD0000">"id" </span><span style="color: #007700">=> </span><span style="color: #0000BB">$id1</span><span style="color: #007700">, </span><span style="color: #DD0000">"name" </span><span style="color: #007700">=> </span><span style="color: #0000BB">$name1</span><span style="color: #007700">] = </span><span style="color: #0000BB">$data</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">];<br /><br /></span><span style="color: #FF8000">// list() style<br /></span><span style="color: #007700">foreach (</span><span style="color: #0000BB">$data </span><span style="color: #007700">as list(</span><span style="color: #DD0000">"id" </span><span style="color: #007700">=> </span><span style="color: #0000BB">$id</span><span style="color: #007700">, </span><span style="color: #DD0000">"name" </span><span style="color: #007700">=> </span><span style="color: #0000BB">$name</span><span style="color: #007700">)) {<br /> </span><span style="color: #FF8000">// logic here with $id and $name<br /></span><span style="color: #007700">}<br /><br /></span><span style="color: #FF8000">// [] style<br /></span><span style="color: #007700">foreach (</span><span style="color: #0000BB">$data </span><span style="color: #007700">as [</span><span style="color: #DD0000">"id" </span><span style="color: #007700">=> </span><span style="color: #0000BB">$id</span><span style="color: #007700">, </span><span style="color: #DD0000">"name" </span><span style="color: #007700">=> </span><span style="color: #0000BB">$name</span><span style="color: #007700">]) {<br /> </span><span style="color: #FF8000">// logic here with $id and $name<br /></span><span style="color: #007700">}</span>
</span>
</code></div>
</div>
</div>
</div>
<div class="sect2" id="migration71.new-features.support-for-negative-string-offsets">
<h3 class="title">Support for negative string offsets</h3>
<p class="para">
Support for negative string offsets has been added to the
<a href="book.strings.html" class="link">string manipulation functions</a>
accepting offsets, as well as to
<a href="language.types.string.html#language.types.string.substr" class="link">string indexing</a> with
<em>[]</em> or <em>{}</em>. In such cases, a negative
offset is interpreted as being an offset from the end of the string.
</p>
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />var_dump</span><span style="color: #007700">(</span><span style="color: #DD0000">"abcdef"</span><span style="color: #007700">[-</span><span style="color: #0000BB">2</span><span style="color: #007700">]);<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">strpos</span><span style="color: #007700">(</span><span style="color: #DD0000">"aabbcc"</span><span style="color: #007700">, </span><span style="color: #DD0000">"b"</span><span style="color: #007700">, -</span><span style="color: #0000BB">3</span><span style="color: #007700">));</span>
</span>
</code></div>
</div>
<p class="para">The above example will output:</p>
<div class="example-contents screen">
<div class="cdata"><pre>
string (1) "e"
int(3)
</pre></div>
</div>
</div>
<p class="para">
Negative string and array offsets are now also supported in the simple
variable parsing syntax inside of strings.
</p>
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$string </span><span style="color: #007700">= </span><span style="color: #DD0000">'bar'</span><span style="color: #007700">;<br />echo </span><span style="color: #DD0000">"The last character of '</span><span style="color: #0000BB">$string</span><span style="color: #DD0000">' is '</span><span style="color: #0000BB">$string</span><span style="color: #007700">[-</span><span style="color: #0000BB">1</span><span style="color: #007700">]</span><span style="color: #DD0000">'.\n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<p class="para">The above example will output:</p>
<div class="example-contents screen">
<div class="cdata"><pre>
The last character of 'bar' is 'r'.
</pre></div>
</div>
</div>
</div>
<div class="sect2" id="migration71.new-features.support-for-aead-in-ext-openssl">
<h3 class="title">Support for AEAD in ext/openssl</h3>
<p class="para">
Support for AEAD (modes GCM and CCM) have been added by extending the
<span class="function"><a href="function.openssl-encrypt.html" class="function">openssl_encrypt()</a></span> and
<span class="function"><a href="function.openssl-decrypt.html" class="function">openssl_decrypt()</a></span> functions with additional parameters.
</p>
</div>
<div class="sect2" id="migration71.new-features.convert-callables-to-closures">
<h3 class="title">Convert callables to <a href="class.closure.html" class="classname">Closure</a>s with <span class="methodname"><a href="closure.fromcallable.html" class="methodname">Closure::fromCallable()</a></span></h3>
<p class="para">
A new static method has been introduced to the <a href="class.closure.html" class="classname">Closure</a>
class to allow for <span class="type"><a href="language.types.callable.html" class="type callable">callable</a></span>s to be easily converted into
<a href="class.closure.html" class="classname">Closure</a> objects.
</p>
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">class </span><span style="color: #0000BB">Test<br /></span><span style="color: #007700">{<br /> public function </span><span style="color: #0000BB">exposeFunction</span><span style="color: #007700">()<br /> {<br /> return </span><span style="color: #0000BB">Closure</span><span style="color: #007700">::</span><span style="color: #0000BB">fromCallable</span><span style="color: #007700">([</span><span style="color: #0000BB">$this</span><span style="color: #007700">, </span><span style="color: #DD0000">'privateFunction'</span><span style="color: #007700">]);<br /> }<br /><br /> private function </span><span style="color: #0000BB">privateFunction</span><span style="color: #007700">(</span><span style="color: #0000BB">$param</span><span style="color: #007700">)<br /> {<br /> </span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$param</span><span style="color: #007700">);<br /> }<br />}<br /><br /></span><span style="color: #0000BB">$privFunc </span><span style="color: #007700">= (new </span><span style="color: #0000BB">Test</span><span style="color: #007700">)-></span><span style="color: #0000BB">exposeFunction</span><span style="color: #007700">();<br /></span><span style="color: #0000BB">$privFunc</span><span style="color: #007700">(</span><span style="color: #DD0000">'some value'</span><span style="color: #007700">);</span>
</span>
</code></div>
</div>
<p class="para">The above example will output:</p>
<div class="example-contents screen">
<div class="cdata"><pre>
string(10) "some value"
</pre></div>
</div>
</div>
</div>
<div class="sect2" id="migration71.new-features.asynchronous-signal-handling">
<h3 class="title">Asynchronous signal handling</h3>
<p class="para">
A new function called <span class="function"><a href="function.pcntl-async-signals.html" class="function">pcntl_async_signals()</a></span> has been
introduced to enable asynchronous signal handling without using ticks (which
introduce a lot of overhead).
</p>
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />pcntl_async_signals</span><span style="color: #007700">(</span><span style="color: #0000BB">true</span><span style="color: #007700">); </span><span style="color: #FF8000">// turn on async signals<br /><br /></span><span style="color: #0000BB">pcntl_signal</span><span style="color: #007700">(</span><span style="color: #0000BB">SIGHUP</span><span style="color: #007700">, function(</span><span style="color: #0000BB">$sig</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">"SIGHUP\n"</span><span style="color: #007700">;<br />});<br /><br /></span><span style="color: #0000BB">posix_kill</span><span style="color: #007700">(</span><span style="color: #0000BB">posix_getpid</span><span style="color: #007700">(), </span><span style="color: #0000BB">SIGHUP</span><span style="color: #007700">);</span>
</span>
</code></div>
</div>
<p class="para">The above example will output:</p>
<div class="example-contents screen">
<div class="cdata"><pre>
SIGHUP
</pre></div>
</div>
</div>
</div>
<div class="sect2" id="migration71.new-features.http2-server-push-support-in-ext-curl">
<h3 class="title">HTTP/2 server push support in ext/curl</h3>
<p class="para">
Support for server push has been added to the CURL extension (requires
version 7.46 and above). This can be leveraged through the
<span class="function"><a href="function.curl-multi-setopt.html" class="function">curl_multi_setopt()</a></span> function with the new
<strong><code>CURLMOPT_PUSHFUNCTION</code></strong> constant. The constants
<strong><code>CURL_PUSH_OK</code></strong> and <strong><code>CURL_PUSH_DENY</code></strong> have also been
added so that the execution of the server push callback can either be
approved or denied.
</p>
</div>
<div class="sect2" id="migration71.new-features.stream-context-options">
<h3 class="title">Stream Context Options</h3>
<p class="para">
The <a href="context.socket.html#context.socket.tcp_nodelay" class="link">tcp_nodelay</a> stream
context option has been added.
</p>
</div>
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