PHP7 new features introduction

We have compiled some commonly used new features, welcome to like! ! !

New operator
1. ??
$username = $_GET['user'] ?? '';
$username = isset($_GET['user']) ? $_GET['user'] : ' nobody';

2. <=>
$number1 <=> $number2; When $number1 is less than, equal to, or greater than $number2, return -1,0,1 respectively

New function
intdiv(divisor, divisor) — round the division result
intdiv(3, 2) //1

define can define arrays
define('ANIMALS', [
'dog',
'cat',
'bird'
]);

Return type declaration
function test() :int
{
return 1; //true
return '1'; //true
return 'string'; //false
}

Scalar type declaration
function test(string $name) :int
{
return 22;
}
string integer float boolean

Can catch core errors
Error hierarchy
Throwable
　Error
　ArithmeticError
　　DivisionByZeroError

　　AssertionError
　　ParseError
　　TypeError

Exception


Optimization of core sorting
php5: array(1=>0, 0=> 0) //Quick sort (unstable sort)
php7: array(0=>0, 1=>0) //Quick sort + selection sort (stable sort)



More abstract syntax than php5 Number (abstract snytax tree) AST
PHP -> Parser -> AST ->Opcodes -> Execution
Performance has increased, memory consumption has also increased but is negligible


Anonymous classes can be instantiated through new class An anonymous class
function getAnonymousClass($config) {
return new class($config) {};
}



Temporarily bind a method to the object and call
$f = function() {
p($ this->name);
};

class F {
private $name = 'F';
}

$f->call(new F);




Unified syntax variables
Brackets do not affect behavior from left to right

$a = 'b';
$b = ['1', '2 ', '3'];
var_dump($$a[1]);
var_dump(($$a)[1]);

php5:
Notice: Uninitialized string offset: 1 in E:Program FilesphpStudyWWWtest.php on line 4
Notice: Undefined variable: in E:Program FilesphpStudyWWWtest.php on line 4
NULL

Parse error: syntax error, unexpected '[' in E:Program FilesphpStudyWWWtest.php on line 4

php7: string(1 ) "2" string(1) "2"


Expression PHP5 PHP7 $$foo['bar']['baz'] ${$foo['bar']['baz']} ($$foo )['bar']['baz']
$foo->$bar['baz'] 　 $foo->{$bar['baz']} 　 ($foo->$bar)['baz ']
$foo->$bar['baz']() 　 $foo->{$bar['baz']}()　 ($foo->$bar)['baz']()
Foo::$bar['baz']() 　 Foo::{$bar['baz']}() 　 (Foo::$bar)['baz']()




About namespaces
/ / Pre PHP 7 code
use somenamespaceClassA;
use somenamespaceClassB;
use somenamespaceClassC as C;

use function somenamespacefn_a;

use function somenamespacefn_b;
use function somenamespacefn_c;

use const somenamespaceConstA;

use const somenamespaceConstB;
use const somenamespaceConstC;

// PHP 7+ code

use somenamespace{ClassA, ClassB, ClassC as C};
use function somenamespace{fn_a, fn_b, fn_c};
use const somenamespace{ConstA, ConstB, ConstC};


modification of list
1.
list($array[], $array[], $array[]) = [1, 2, 3];
var_dump($array);
php5: array(3) { [0]=> ; int(3) [1]=> int(2) [2]=> int(1) }
　　php7: array(3) { [0]=> int(1) [1]=> int(2) [2]=> int(3) }


2. Assigning null value is not allowed
list() = $a;
list(,,) = $a;
list($x, list (), $y) = $a;

php7 will report Fatal error: Cannot use empty list

3. String splitting is no longer supported
$string = "xy";
list($x, $y) = $string;
var_dump($x, $y);

php5: string(1) "x" string(1) "y"
php7: null null

Modification of foreach
Variable reference will affect the array Loop of
$array = [0];
foreach ($array as &$val) {
var_dump($val);
$array[1] = 1;
}
php5: int(0)
php7: int (0) int(1)

Reference source address: http://www.php7.site/book/php7/variable-changes-22.html

Tips to improve PHP performance: http://www.laruence.com/2015/12/04/3086.html