What are the differences between the version of php7 and 5?

The differences between the version of php7 and 5 include performance improvements, scalar type declarations, return value type declarations, exception handling improvements, anonymous classes, syntax improvements, new operators, enhanced error handling and the removal of some Old features etc. Detailed introduction: 1. Performance improvement. PHP7 introduces a new Zend engine, named Zend Engine 3.0, which brings significant performance improvement. The performance of PHP7 is approximately twice that of PHP5, mainly through improved memory management. , optimized function calls and exception handling, enhanced garbage collection, etc.

The operating system of this tutorial: Windows10 system, PHP version 8.1.3, DELL G3 computer.

PHP 7 is an important version of the PHP programming language. Compared with PHP 5, it introduces many new features and improvements, with significant improvements and changes from performance to syntax. Here are some important differences between PHP 7 and PHP 5:

1. Performance improvements: PHP 7 introduces a new Zend engine, called Zend Engine 3.0, which brings significant performance improvements . The performance of PHP 7 is approximately twice that of PHP 5, which is mainly achieved through improved memory management, optimized function calls and exception handling, and enhanced garbage collection.

2. Scalar type declaration: PHP 7 introduced scalar type declaration, allowing developers to specify the expected data types on function parameters and return values. This includes four scalar types: int, float, string, and bool. Through type declaration, you can improve the readability and maintainability of your code and reduce bugs caused by type errors.

3. Return value type declaration: PHP 7 also introduces return value type declaration, allowing developers to specify the return value type of a function in the function definition. In this way, you can ensure that the value returned by the function conforms to the expected type, improving the reliability and maintainability of the code.

4. Exception handling improvements: PHP 7 has improved exception handling and introduced a new exception class Throwable, which is the base class of all exception classes. This makes exception handling more consistent and flexible, and developers can better handle and catch exceptions.

5. Anonymous classes: PHP 7 introduced the concept of anonymous classes, allowing instances of classes to be created without defining a specific class name. This is useful for simple classes or classes that need to be created temporarily.

6. Syntax improvements: PHP 7 has made some improvements and simplifications to the syntax. For example, constant array definitions are allowed, error handling syntax is simplified, and more concise syntax is provided for handling nullable properties and parameters.

7. New operators: PHP 7 introduces some new operators, such as the spaceship operator (<=>), which is used to compare the size relationship between two expressions and return - 1, 0 or 1.

8. Enhanced error handling: PHP 7 improves the error handling mechanism and introduces strict mode, making errors easier to find and fix. In strict mode, some potential errors and irregular code will be warned or exceptions will be thrown.

9. Some old features have been removed: In order to improve code quality and security, PHP 7 has removed some outdated or deprecated features. For example, the mysql_ series of functions have been removed, and it is recommended to use mysqli_ or PDO extensions instead.

It should be noted that since PHP 7 introduces some new features and syntax changes that are incompatible with PHP 5, you need to carefully check and test the existing code before upgrading to PHP 7 to ensure that it It can run normally under PHP 7. At the same time, we should also pay attention to the performance improvements and syntax changes of PHP 7 compared to PHP 5, so as to make full use of the advantages of the new version and improve the quality and performance of the code.

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