New Features of PHP 7.0 and php7.0

New Features of PHP 7.0 and php7.0

?? The operator (NULL merge operator) puts this in the first example because I think it is very useful. Usage: $ a = $ _ GET ['a']? 1; it is equivalent to: <? PHP $ a = isset ($ _ GET ['a'])? $ _ GET ['a']: 1; we know that the ternary operator can be used as follows: $? : 1, but this is based on the premise that $ a has been defined.

?? Operator (NULL merge operator)

Put this in the first example because I think it is useful. Usage:

$a = $_GET['a'] ?? 1; It is equivalent:

<?php $a = isset($_GET['a']) ? $_GET['a'] : 1; We know that the ternary operator can be used like this:

$? : 1, but this is based on the premise that $ a has been defined. New ?? Operators can simplify judgment.

1. function return value type declaration

Examples provided in the official documentation (note that the edge length parameter syntax is only available in PHP 5.6 or later versions ):

<? Php function arraysSum (array... $ arrays): array {return array_map (function (array $ array): int {return array_sum ($ array) ;}, $ arrays);} print_r (arraysSum ([1, 2, 3], [, 6], [, 9]). From this example, we can see that all functions (including anonymous functions) can specify the type of the returned value.

The statement is written in a way similar to Swift:

func sayHello(personName: String) -> String { let greeting = "Hello, " + personName + "!" return greeting } This feature helps us avoid some problems caused by implicit type conversion in PHP. You can think about the expected results before defining a function to avoid unnecessary errors.

However, there is also a feature that requires attention. PHP 7 adds a declare command: strict_types, which uses both the strict mode.

When using the return value type declaration, if it is not declared as the strict mode, if the return value is not the expected type, PHP will still forcibly convert it to the type. However, if the mode is strict, a Fatal error of TypeError is triggered.

Force mode:

<?php function foo($a) : int { return $a; } foo(1.0); The above code can be executed normally. The foo function returns int 1 without any errors.

Strict mode:

<?php declare(strict_types=1); function foo($a) : int { return $a; } foo(1.0);

PHP Fatal error: Uncaught TypeError: Return value of foo () must be of the type integer, float returned in test. php: 6

After the declaration, a fatal error is triggered.

Is it a bit similar to the strict mode of js?

Scalar type declaration

The parameter type declaration of a function in PHP 7 can be a scalar. In PHP 5, it can only be a class name, interface, array, or callable (PHP 5.4, which can be a function, including an anonymous function ), now you can also use string, int, float, and bool.

Official example:

<?php // Coercive mode function sumOfInts(int ...$ints) { return array_sum($ints); } var_dump(sumOfInts(2, '3', 4.1));

It should be noted that the strict mode mentioned above is also applicable here: the forced type conversion will still be performed for parameters that do not meet expectations in the forced mode (default, both forced type conversion, in strict mode, the critical error of TypeError is triggered.

1. use batch Declaration

In PHP 7, use can declare multiple classes, functions, or const in one sentence:

<? Php 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}; but you still need to write the name of each class or function or const (there is no from some import * method like Python ).

It should be noted that if you are using a composer-based and PSR-4-based framework, can this method successfully load class files? In fact, it is okay. The automatic loading method registered by composer is to find the location based on the namespace of the class when the class is called. This method has no effect on it.

Other features

I will not introduce some other features one by one, interested can view the official documentation: http://php.net/manual/en/migration70.new-features.php

Briefly speaking:

PHP 5.3 has an anonymous function and now has an anonymous class. define can now define a constant array, and the Closure (Closure) adds a call method; the generator (or the iterator is more suitable) can have a final return value (return), or enter another generator (generator delegate) through the new syntax of yield from ). The two new features of the generator (return and yield from) can be combined. You can test the specific representation on your own. PHP 7 has now reached RC5, and the final version will soon come.

The above is an introduction to the new features of PHP 7.0 introduced by xiaobian. I hope it will be helpful to you. If you have any questions, please leave a message and I will reply to you in a timely manner. Thank you very much for your support for the help House website!