What are the new features of php7?

What are the new features of php7? In PHP7, because most of the code of the underlying engine has been modified and the performance of PHP has been improved through various methods, some new syntax has been added to PHP7. The use of these syntax can also help improve performance. Here is a brief introduction to you, I hope it will be helpful to you.

1. Scalar parameter type declaration

You can use string (string), integer (int), floating point number (float), and Boolean value (bool), To declare the parameter type and function return value of the function; previously only two styles of class name, interface, array and Callable were supported: forced conversion mode (default) and strict mode

declare(strict_types=1);
function add(int $a, int $b): int {
    return $a+$b;
}
 
echo add(1, 2);
echo add(1.5, 2.6);

php5 cannot execute the above code. When php7 is executed, it will first output a 3 and an error (Argument 1 passed to add() must be of the type integer, float given);

There are two modes for scalar type declarations : Enforcement (default) and strict mode.

declare(strict_types=1), must be placed on the first line of the file to execute the code, the current file is valid!

2. set_exception_handler() no longer guarantees that what is received must be an Exception object

In PHP 7, there are many fatal errors and recoverable fatal errors , are converted into exceptions for processing. These exceptions inherit from the Error class, which implements the Throwable interface (all exceptions implement this base interface).

PHP7 further facilitates developers' processing and allows developers to have greater control over the program. Because by default, Error will directly cause the program to interrupt, while PHP7 provides the ability to capture and process it, allowing the program to continue. The implementation continues to provide programmers with more flexible options.

3. New operator "<=>"

Syntax:

$c = $a <=> $b

If $a > $b, $c The value is 1

If $a == $b, the value of $c is 0

If $a < $b, the value of $c is -1

4. New operator "??"

If the variable exists and the value is not NULL, it will return its own value, otherwise Returns its second operand.

//原写法
$username = isset($_GET['user]) ? $_GET['user] : 'nobody';
//现在
$username = $_GET['user'] ?? 'nobody';
5.define() 定义常量数组
define('ARR',['a','b']);
echo ARR[1];// a

6. AST: Abstract Syntax Tree, Abstract Syntax Tree

AST plays the role of a middleware in the PHP compilation process, replacing the original output of opcode directly from the interpreter. This way, the interpreter (parser) and the compiler (compliler) are decoupled, which can reduce some Hack code, and at the same time, make the implementation easier to understand and maintain.

PHP5: PHP code-> Parser syntax Parsing-> OPCODE -> Execute

PHP7: PHP code-> Parser syntax analysis-> AST -> OPCODE -> Execute

7, anonymous function

$anonymous_func = function(){return 'function';};
echo $anonymous_func(); // 输出function

8. Unicode character format support (echo “\u{9999}”)

9. Unserialize provides filtering features

Prevents code injection of illegal data and provides safer deserialized data.

10. Namespace reference optimization

// PHP7以前语法的写法 
use FooLibrary\Bar\Baz\ClassA; 
use FooLibrary\Bar\Baz\ClassB; 

// PHP7新语法写法 
use FooLibrary\Bar\Baz\{ ClassA, ClassB};

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