How to solve the compatibility errors that may occur during the upgrade process of PHP7.4

How to solve the compatibility errors that may occur during the upgrade process of PHP7.4

With the development and upgrade of technology, PHP 7.4 version has been released. It brings some new features and improvements, so many developers want to upgrade their projects to this version. However, there may be some compatibility bugs when upgrading to PHP 7.4, which will require some tweaking and resolution.

Below we will provide some methods to solve PHP 7.4 compatibility errors, with code examples.

1. Check for obsolete functions and features
   PHP 7.4 made many meaningful changes, some of which have been deprecated or removed. Before upgrading, you need to check your code for use of these outdated functions and features and change them accordingly.

Sample code:

// PHP 7.4 移除了原有的 preg_replace 函数中的 /e 修饰符，你需要更改你的代码：

$string = 'Hello, World!';
$pattern = '/Hello/';
$replacement = 'Hi';

// 在 PHP 7.4 之前的版本
$result = preg_replace('/Hello/', 'Hi', $string); // 使用 /e 修饰符

// 在 PHP 7.4 版本
$result = preg_replace_callback(
    $pattern,
    function ($matches) use ($replacement) {
        return $replacement;
    },
    $string
);

2. New reserved keywords
   PHP 7.4 introduces some new reserved keywords, which may cause your The code has a syntax error after the upgrade. You need to avoid using these keywords as names in your classes, methods or properties. If you are not sure whether you have used these keywords, you can use the token_get_all() function to check.

Sample code:

// 以下是 PHP 7.4 引入的一些新的预留关键字，请避免在代码中使用这些关键字作为名称
$keywords = ['static', 'mixed', 'bool', 'int', 'float', 'string', 'object', 'iterable', 'self', 'parent'];

3. Naming conflicts between classes and interfaces
   Names can already be shared between classes and interfaces in PHP 7.4, which may cause problems after upgrading A naming conflict has occurred. You need to check whether there are classes and interfaces with the same name in your code and rename them accordingly.

Sample Code:

// PHP 7.4 之前
class MyClass {
    // ...
}

interface MyClass {
    // ...
}

// PHP 7.4 之后
class MyClass {
    // ...
}

interface MyClass2 {
    // ...
}

4. Changing Error Reporting Level
   In PHP 7.4, some errors that originally produced warnings were promoted to fatal errors, meaning that they Execution of the script stops and an error message is displayed. If these errors exist in your code, you will need to change the error reporting level on a case-by-case basis and handle the errors accordingly.

Sample code:

// 一些警告在 PHP 7.4 中被提升为致命错误，你可以使用错误控制运算符 @ 来忽略这些错误

@ini_set('display_errors', '0');

Before upgrading to PHP 7.4, be sure to back up your code and database and test the upgraded code thoroughly. If you encounter other compatibility errors, you can refer to the official PHP documentation or community forums for more solutions.

Summary:
PHP 7.4 brings some new features and improvements, but it may also cause some compatibility errors. Before upgrading to PHP 7.4, you need to check and change your code for possible obsolete functions and features, new reserved keywords, naming conflicts of classes and interfaces, and modify the error reporting level accordingly. Through these methods, you can more smoothly solve the compatibility errors that may occur during the upgrade process of PHP 7.4.

I hope this article will help you solve PHP 7.4 compatibility errors!

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