新的特性
新增 Generators
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):
<?php
function xrange($start, $limit, $step = 1) {
for ($i = $start; $i <= $limit; $i += $step) {
yield $i;
}
}
echo 'Single digit odd numbers: ';
/* 注意保存在内存中的数组绝不会被创建或返回 */
foreach (xrange(1, 9, 2) as $number) {
echo "$number ";
}
?>
以上例程会输出：
Single digit odd numbers: 1 3 5 7 9
新增 finally 关键字
try-catch blocks now support a finally block for code that should be run regardless of whether an exception has been thrown or not.
foreach 现在支持 list()
foreach 控制结构现在支持通过 list() 构造将嵌套数组分离到单独的变量。例如：
<?php
$array = [
[1, 2],
[3, 4],
];
foreach ($array as list($a, $b)) {
echo "A: $a; B: $b\n";
}
?>
以上例程会输出：
A: 1; B: 2 A: 3; B: 4
关于 foreach 更深入的文档可参考相关手册页面。
empty() 支持任意表达式
empty() 现在支持传入一个任意表达式，而不仅是一个变量。例如：
<?php
function always_false() {
return false;
}
if (empty(always_false())) {
echo 'This will be printed.';
}
if (empty(true)) {
echo 'This will not be printed.';
}
?>
以上例程会输出：
This will be printed.
array and string literal dereferencing
Array and string literals can now be dereferenced directly to access individual elements and characters:
<?php
echo 'Array dereferencing: ';
echo [1, 2, 3][0];
echo "\n";
echo 'String dereferencing: ';
echo 'PHP'[0];
echo "\n";
?>
以上例程会输出：
Array dereferencing: 1 String dereferencing: P
新的密码哈希 API
A 新的密码哈希 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.
Apache 2.4 handler supported on Windows
The Apache 2.4 handler SAPI is now supported on Windows.
改进 GD
对 GD 扩展做了多方面的改进，包括：
翻转支持使用新的 imageflip() 函数。 高级裁剪支持使用 imagecrop() & imagecropauto() 函数。 WebP 的读写分别支持使用 imagecreatefromwebp() & imagewebp() 。User Contributed Notes 3 notes
up down 13 PHP Guy ¶5 years ago
Great work. Thank you for allowing Lists to return on foreach.
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1
Anonymous ¶4 years ago
Yield is awesome... it's starts to look like a real language now ;-)
class myList {
public $list;
public function __construct($list) {
$this->list = $list;
}
public function select(...$keys) {
$keys_array = array_fill_keys($keys, null);
$items = $this->list;
foreach($items as $item) {
yield array_merge($keys_array, array_intersect_key($item, $keys_array));
}
}
}
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0
wallacemaxters at gmail dot com ¶2 years ago
After PHP 5.5, foreach with reference in arbitrary array does not generate an error:
foreach ([1, 2, 3, 4] as $key => &$value) {
$value = $value . ' R$';
}
before 5.4, will generate "Cannot create references to elements of a temporary array expression"
add a note
官方地址：https://www.php.net/manual/en/migration55.new-features.php