What has changed in PHP 5.5.x
1.Generators added
Support for generators has been
added via the yield keyword. Generators provide an easy
way to implement simple iterators without the overhead or complexity of
implementing a class that implements the Iterator
interface.
A simple example that reimplements the range()
function as a generator (at least for positive step
values):
<?phpfunction xrange($start, $limit, $step = 1) {
for ($i = $start; $i <= $limit; $i += $step) {
yield $i;
}
}
echo 'Single digit odd numbers: ';/*
* Note that an array is never created or returned,
* which saves memory.
*/foreach (xrange(1, 9, 2) as $number) {
echo "$number ";
}
echo "\n";?>
for ($i = $start; $i <= $limit; $i += $step) {
yield $i;
}
}
echo 'Single digit odd numbers: ';/*
* Note that an array is never created or returned,
* which saves memory.
*/foreach (xrange(1, 9, 2) as $number) {
echo "$number ";
}
echo "\n";?>
The above example will output:
Single digit odd numbers: 1 3 5 7 9
2.finally keyword added
try-catch blocks now support a finally block for code that should be
run regardless of whether an exception has been thrown or not.
3.New password hashing API
A new password hashing API that makes
it easier to securely hash and manage passwords using the same underlying
library as crypt() in PHP has been added. See the
documentation for password_hash() for more detail.
4.foreach now supports list()
The foreach control
structure now supports unpacking nested arrays into separate variables via
the list() construct. For example:
<?php
$array = [
[1, 2],
[3, 4],
];
foreach ($array as list($a, $b)) {
echo "A: $a; B: $b\n";
}?>
The above example will output:
A: 1; B: 2
A: 3; B: 4
Further documentation is available on the
foreach manual
page.
5.empty() supports arbitrary expressions
Passing an arbitrary expression instead of a variable to
empty() is now supported. For example:
<?phpfunction always_false() {
return false;
}
if (empty(always_false())) {
echo "This will be printed.\n";
}
if (empty(true)) {
echo "This will not be printed.\n";
}?>
The above example will output:
This will be printed.
6.array and string literal dereferencing
Array and string literals can now be
dereferenced directly to access individual elements and characters:
<?phpecho 'Array dereferencing: ';
echo [1, 2, 3][0];
echo "\n";
echo 'String dereferencing: ';
echo 'PHP'[0];
echo "\n";?>
The above example will output:
Array dereferencing: 1
String dereferencing: P
7.Class name resolution via ::class
It is possible to use ClassName::class to get a fully
qualified name of class ClassName. For example:
<?phpnamespace Name\Space;
class ClassName {}
echo ClassName::class;
echo "\n";?>
class ClassName {}
echo ClassName::class;
echo "\n";?>
The above example will output:
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