This article introduces the new features of PHP5.5 ~ PHP7.2. Friends in need can refer to it
Porting from PHP 5.5.x to PHP 5.6.x
New Features
Use expressions to define constants
In previous versions of PHP, you had to use static values to define constants, declare properties, and specify default values for function parameters. You can now use numeric expressions including numbers, string literals, and other constants to define constants, declare properties, and set default values for function parameters.
<?php
const ONE = 1;
const TWO = ONE * 2;
class C {
const THREE = TWO + 1;
const ONE_THIRD = ONE / self::THREE;
const SENTENCE = 'The value of THREE is '.self::THREE;
}Copy after login
<?php
const ARR = ['a', 'b'];
echo ARR[0];
Copy after login
Use ... operators to define variable-length parameter functions
<?php
function f($req, $opt = null, ...$params) {
// $params 是一个包含了剩余参数的数组
printf('$req: %d; $opt: %d; number of params: %d'."\n",
$req, $opt, count($params));
}
f(1);
f(1, 2);
f(1, 2, 3);
f(1, 2, 3, 4);
?>Copy after login
The above routine will output:
$req: 1; $opt: 0; number of params: 0
$req: 1; $opt: 2; number of params: 0
$req: 1; $opt: 2; number of params: 1
$req: 1; $opt: 2; number of params: 2
Copy after login
Use the ... operator for parameter expansion
-
When calling a function, use the... operator to expand arrays and traversable objects into function parameters. In other programming languages, such as Ruby, this is called the concatenation operator.
<?php
function add($a, $b, $c) {
return $a + $b + $c;
}
$operators = [2, 3];
echo add(1, ...$operators);
?>Copy after login
The above routine will output:
use function and use const
<?php
namespace Name\Space {
const FOO = 42;
function f() { echo __FUNCTION__."\n"; }
}
namespace {
use const Name\Space\FOO;
use function Name\Space\f;
echo FOO."\n";
f();
}
?>Copy after login
The above routine will output:
42
Name\Space\f
Copy after login
Use hash_equals() to compare strings to avoid timing attacks
Ported from PHP 5.6.x to PHP 7.0.x
New features
Scalar type declaration
There are two modes for scalar type declaration: mandatory (default) and strict mode. The following type parameters are now available (either in forced or strict mode): string, int, float, and bool.
<?php
// Coercive mode
function sumOfInts(int ...$ints)
{
return array_sum($ints);
}
var_dump(sumOfInts(2, '3', 4.1));Copy after login
The above routine will output:
Return value type declaration
<?php
function arraysSum(array ...$arrays): array
{
return array_map(function(array $array): int {
return array_sum($array);
}, $arrays);
}Copy after login
null coalescing operator
Since there are a lot of situations where ternary expressions and isset() are used simultaneously in daily use, we add The syntactic sugar of null coalescing operator (??) is added. If the variable exists and is not NULL, it returns its own value, otherwise it returns its second operand.
<?php
// Fetches the value of $_GET['user'] and returns 'nobody' if it does not exist.
$username = $_GET['user'] ?? 'nobody';
// This is equivalent to:
$username = isset($_GET['user']) ? $_GET['user'] : 'nobody';
// Coalesces can be chained: this will return the first defined value out of $_GET['user'], $_POST['user'], and 'nobody'.
$username = $_GET['user'] ?? $_POST['user'] ?? 'nobody';
?>
Copy after login
Spaceship operator (combined comparison operator)
The spaceship operator is used to compare two expressions. It returns -1, 0 or 1 when $a is less than, equal to or greater than $b respectively. The principle of comparison follows PHP's regular comparison rules.
<?php
// 整数
echo 1 <=> '1'; // 0
echo 1 <=> 2; // -1
echo 2 <=> 1; // 1
// 浮点数
echo '1.50' <=> 1.5; // 0
echo 1.5 <=> 2.5; // -1
echo 2.5 <=> 1.5; // 1
// 字符串
echo "a" <=> "a"; // 0
echo "a" <=> "b"; // -1
echo "b" <=> "a"; // 1
?>
Copy after login
Defining constant arrays via define()
define('ANIMALS', [
'dog',
'cat',
'bird'
]);
echo ANIMALS[1]; // 输出 "cat"Copy after login
Closure::call()
<?php
class A {private $x = 1;}
// PHP 7 之前版本的代码
$getXCB = function() {return $this->x;};
$getX = $getXCB->bindTo(new A, 'A'); // 中间层闭包
echo $getX();
// PHP 7+ 及更高版本的代码
$getX = function() {return $this->x;};
echo $getX->call(new A);Copy after login
The above routine will output:
Groupinguse Statement
<?php
// PHP 7 之前的代码
use some\namespace\ClassA;
use some\namespace\ClassB;
use some\namespace\ClassC as C;
use function some\namespace\fn_a;
use function some\namespace\fn_b;
use function some\namespace\fn_c;
use const some\namespace\ConstA;
use const some\namespace\ConstB;
use const some\namespace\ConstC;
// PHP 7+ 及更高版本的代码
use some\namespace\{ClassA, ClassB, ClassC as C};
use function some\namespace\{fn_a, fn_b, fn_c};
use const some\namespace\{ConstA, ConstB, ConstC};
?>Copy after login
Generators can return expressions
This feature builds on the generator feature introduced in PHP 5.5 version. It allows you to return an expression by using the return syntax in a generator function (but does not allow the return of a reference value). You can get the return value of the generator by calling the Generator::getReturn() method, but this method can only be used when generating Called once after the generator has finished generating work.
Integer division function intp()
Ported from PHP 7.0.x to PHP 7.1.x
New features
Nullable type
<?php
function testReturn(): ?string
{
return 'elePHPant';
}
var_dump(testReturn());
function testReturn(): ?string
{
return null;
}
var_dump(testReturn());
function test(?string $name)
{
var_dump($name);
}
test('elePHPant');
test(null);
test();Copy after login
The above routine will output:
string(10) "elePHPant"
NULL
string(10) "elePHPant"
NULL
Uncaught Error: Too few arguments to function test(), 0 passed in...
Copy after login
Void function
<?php
function swap(&$left, &$right) : void
{
if ($left === $right) {
return;
}
$tmp = $left;
$left = $right;
$right = $tmp;
}
$a = 1;
$b = 2;
var_dump(swap($a, $b), $a, $b);Copy after login
The above routine will output:
null
int(2)
int(1)
Copy after login
Symmetric array destructuring
<?php
$data = [
[1, 'Tom'],
[2, 'Fred'],
];
// list() style
list($id1, $name1) = $data[0];
// [] style
[$id1, $name1] = $data[0];
// list() style
foreach ($data as list($id, $name)) {
// logic here with $id and $name
}
// [] style
foreach ($data as [$id, $name]) {
// logic here with $id and $name
}Copy after login
类常量可见性
<?php
class ConstDemo
{
const PUBLIC_CONST_A = 1;
public const PUBLIC_CONST_B = 2;
protected const PROTECTED_CONST = 3;
private const PRIVATE_CONST = 4;
}Copy after login
iterable 伪类
<?php
function iterator(iterable $iter) : iterable
{
foreach ($iter as $val) {
//
}
}Copy after login
多异常捕获处理
<?php
try {
// some code
} catch (FirstException | SecondException $e) {
// handle first and second exceptions
}Copy after login
list()现在支持键名
<?php
$data = [
["id" => 1, "name" => 'Tom'],
["id" => 2, "name" => 'Fred'],
];
// list() style
list("id" => $id1, "name" => $name1) = $data[0];
// [] style
["id" => $id1, "name" => $name1] = $data[0];
// list() style
foreach ($data as list("id" => $id, "name" => $name)) {
// logic here with $id and $name
}
// [] style
foreach ($data as ["id" => $id, "name" => $name]) {
// logic here with $id and $name
}Copy after login
从PHP 7.1.x 移植到 PHP 7.2.x
新特性
新的对象类型
<?php
function test(object $obj) : object
{
return new SplQueue();
}
test(new StdClass());Copy after login
允许重写抽象方法(Abstract method)
abstract class A
{
abstract function test(string $s);
}
abstract class B extends A
{
// overridden - still maintaining contravariance for parameters and covariance for return
abstract function test($s) : int;
}Copy after login
扩展了参数类型
interface A
{
public function Test(array $input);
}
class B implements A
{
public function Test($input){} // type omitted for $input
}Copy after login
允许分组命名空间的尾部逗号
use Foo\Bar\{
Foo,
Bar,
Baz,
};Copy after login
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