详解PHP7新特性 What will be in PHP 7

1. Introduction

PHP 7 is the latest version of the popular server-side scripting language PHP. It comes with several new features and improvements that enhance its performance and make it a more efficient and powerful programming language. In this article, we will explore some of the key new features in PHP 7.

2. Performance Improvements

One of the major improvements in PHP 7 is its enhanced performance. PHP 7 boasts a new internal engine called the Zend Engine 3.0, which significantly improves the execution speed of PHP scripts. It achieves this by implementing a new abstract syntax tree (AST) based interpreter. This results in faster script execution and improved memory usage.

3. Scalar Type Declarations

3.1 Strong Typing for Parameters and Return Types

PHP 7 introduces scalar type declarations for function parameters and return types. This allows developers to specify the data types of scalar values (such as int, float, string, and bool) that are passed to functions and returned by functions.

function calculateSum(int $a, int $b): int {
    return $a + $b;
}

The example above demonstrates a function that takes two integer parameters and returns an integer value. The scalar type declarations ensure that only integers can be passed as arguments to the function and only an integer will be returned by the function.

4. Null Coalescing Operator

PHP 7 introduces the null coalescing operator (??), which is a shorthand way of checking if a value is null and providing a default value if it is. This helps in writing more concise and readable code.

$userName = $_GET['username'] ?? 'Guest';

In the above example, if the 'username' query parameter is not set or is null, the value 'Guest' will be assigned to the $userName variable. This eliminates the need for conditional checks and provides a default value in a single line of code.

5. Anonymous Classes

PHP 7 introduces support for anonymous classes, which are classes without a named identifier. These classes can be instantiated and used on-the-fly without the need for defining a separate class.

$logger = new class {
    public function log(string $message) {
        echo $message;
    }
};
$logger->log('Hello, World!');

In the example above, an anonymous class is created and an object of that class is instantiated. The log() method of the anonymous class is then called to output the message "Hello, World!". Anonymous classes are useful in scenarios where you need a one-time class implementation.

6. Return Type Declarations

Prior to PHP 7, developers could only specify the return type of a function in the function's documentation. With PHP 7, return type declarations allow developers to specify the expected return type directly in the function declaration.

function multiply(int $a, int $b): int {
    return $a * $b;
}

The above example declares a function named multiply() that takes two integer parameters and returns an integer value. The return type declaration ensures that only an integer is returned by the function.

7. Conclusion

PHP 7 brings several new features and improvements to the table, including enhanced performance, scalar type declarations, the null coalescing operator, anonymous classes, and return type declarations. These additions make PHP 7 a more powerful and efficient programming language for developing web applications.

It is important for developers to understand and leverage these new features to take full advantage of the capabilities offered by PHP 7.