A brief introduction to the new features of PHP 7.0

This article mainly introduces the newly added features of PHP 7.0. Friends who need it can refer to it

?? Operator (NULL merge operator) I put this first because I Found it useful. Usage: $a = $_GET['a'] ?? 1; It is equivalent to:

?? Operator (NULL coalescing operator)

Put this first because I find it 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 like this:

$a ?: 1 But this is based on On the premise that $a has already been defined. The new ?? operator can simplify judgment.

1. Function return value type declaration

The example provided by the official document (note...The side length parameter syntax is in Only available in PHP 5.6 and above):

The way this statement is written is somewhat similar to Swift:

func sayHello(personName: String) -> String { let greeting = "Hello, " + personName + "!" return greeting } This feature can help us avoid some problems caused by PHP's implicit type conversion. Thinking about the expected results before defining a function can avoid unnecessary mistakes.

But there is also a feature that needs attention here. PHP 7 adds a declare directive: strict_types, which uses strict mode.

When using return value type declaration, if it is not declared in strict mode, and if the return value is not the expected type, PHP will still perform cast type conversion on it. But if it is strict mode, a Fatal error of TypeError will be triggered.

Forced mode:

## The above code can be executed normally, and 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 will be triggered.

Is it similar to the strict mode of js?

Scalar type declaration

The formal parameter type declaration of functions in PHP 7 can now be scalar. In PHP 5, it can only be a class name, interface, array or callable (PHP 5.4, it can be a function, including anonymous functions). 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, &#39;3&#39;, 4.1));

It should be noted that the strict mode problems mentioned above are the same here. Applicable: In forced mode (default, which is forced type conversion), parameters that do not meet the expected type will still be forced to type conversion. In strict mode, a fatal TypeError error will be triggered.

1.use batch declaration

In PHP 7, use can declare multiple classes or 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}; 但还是要写出每个类或函数或 const 的名称（并没有像 Python 一样的 from some import * 的方法）。

The issue you need to pay attention to is: if you are using a framework based on composer and PSR-4, whether this writing method can successfully load class files ? In fact, it is possible. The autoloading method registered by composer searches for the location according to the namespace of the class when the class is called. This way of writing has no effect on it.

Other features

I won’t introduce some other features one by one. If you are interested, you can check the official documentation: http ://php.net/manual/en/migration70.new-features.php

Let’s briefly talk about a few:

PHP 5.3 Start With anonymous functions, there are now anonymous classes; define can now define constant arrays; closures have a call method; generators (or iterators more appropriately) can have a final return value (return) , or you can enter another generator (generator delegate) through the new syntax of yield from. Two new features of generators (return and yield from) can be combined. You can test the specific appearance by yourself. PHP 7 is now at RC5 and the final version should be coming soon.

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