How to migrate PHP5.6 code to PHP7.4 to solve compatibility issues?

How to migrate PHP5.6 code to PHP7.4 to solve compatibility issues?

As time goes by, the PHP language continues to develop and release new versions, among which PHP7.4 is currently the most widely used version. However, many developers may still be using the older PHP5.6 version, which raises the question: How to migrate existing PHP5.6 code to PHP7.4 to solve compatibility issues?

This article will discuss some common PHP5.6 code compatibility issues and provide corresponding migration plans and sample codes.

1. Modify the MySQL connection function

In PHP5.6, we usually use the mysql_ series of functions to connect and operate the MySQL database. However, this function series has been deprecated in PHP7.4. We need to replace it with mysqli_ or PDO series functions.

Sample code:

// PHP5.6
$conn = mysql_connect($host, $user, $password);
mysql_select_db($dbname, $conn);
$result = mysql_query($sql, $conn);

Migrate code to PHP7.4:

// PHP7.4
$conn = mysqli_connect($host, $user, $password, $dbname);
$result = mysqli_query($conn, $sql);

2. Modify error handling mechanism

In PHP7.4 , the error handling mechanism has been made some adjustments. In the past, we usually used the error_reporting and set_error_handler functions to handle errors. In PHP7.4, we need to use the error_reporting function and the set_exception_handler function for error handling.

Sample code:

// PHP5.6
error_reporting(E_ALL);
set_error_handler('my_error_handler');

function my_error_handler($errno, $errstr, $errfile, $errline) {
    // 错误处理逻辑
}

// PHP7.4
error_reporting(E_ALL);
set_exception_handler('my_exception_handler');

function my_exception_handler($exception) {
    // 错误处理逻辑
}

3. Replacement of deprecated functions

There are some in PHP7.4 that are still available in PHP5.6 but have been deprecated function, we need to replace it with a new replacement function.

Sample code:

// PHP5.6
mysql_real_escape_string($str);

// PHP7.4
mysqli_real_escape_string($conn, $str);

4. Modify class and method names

In PHP7.4, some class and method names that are considered unsafe have been Abandoned or cancelled. We need to replace these class and method names with new names.

Sample code:

// PHP5.6
class myClass extends AnotherClass {
    // 类定义
}

// PHP7.4
class myClass extends NewClass {
    // 类定义
}

5. Modify array initialization syntax

In PHP7.4, there are some changes in the initialization syntax of empty arrays. We need to replace the old array initialization syntax with the new syntax.

Sample code:

// PHP5.6
$arr = array();

// PHP7.4
$arr = [];

Before migrating the code, we recommend backing up the existing code and migrating it step by step. During the migration process, we can use the error reporting mechanism of PHP7.4 to help us find existing problems. At the same time, you can also use some automated tools to assist migration, such as PHP CodeSniffer and PHPStan.

To summarize, migrating PHP5.6 code to PHP7.4 can solve compatibility problems by modifying MySQL connection functions, modifying error handling mechanisms, replacing abandoned functions, modifying class and method names, and modifying array initialization syntax. Sexual issues. We hope that the migration plan and sample code provided in this article can help developers successfully complete the migration work.

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