How are functions in PHP libraries versioned?

The functions in the PHP function library have version numbers (n.m.g), which represent their historical changes in different PHP versions. A function version number change indicates a change or extension to the function, including adding or removing parameters, changing signatures, changing behavior, or fixing bugs. Use the phpinfo() function to obtain function and version information. For example, the array_keys() function is available in PHP 3.0.0 and higher versions, but not before PHP 4.0.6. Between PHP 7.4.0 and 7.4.x versions There are no changes, while changes were made in the PHP 8.0.0 version.

Versioning of functions in the PHP function library

In the PHP function library, each function has a version number. Indicates the change history of this function in different PHP versions. The version number is in the format n.m.g, where:

• n: major version number
• m: minor version No.
• g: Micro version number

The impact of version upgrade on the function

Changes in the function version number indicate Significant changes or extensions to the function itself. These changes might be:

• Add or remove parameters
• Change function signature
• Change function behavior
• Fix bugs or bugs

Getting the function version number

You can use the phpinfo() function to get information about the function and its version. For the array_keys() function, the result is as follows:

array_keys
Array
(
    [0] => PHP 3 >= 3.0.0
    [1] => PHP 4 >= 4.0.6
    [2] => PHP 7.4 >= 7.4.0
    [3] => PHP 8.0 => PHP 8.0.0
)

This means that the array_keys() function is available in PHP 3.0.0 and above, but not in PHP 4.0 Not available before .6. It also states that this function has not changed between PHP 7.4.0 and 7.4.x versions, but has been changed in PHP 8.0.0 version.

Practical case

Check function availability

if (function_exists('array_diff')) {
    // array_diff() 函数可用
}

Get function version information

echo phpinfo(INFO_MODULES);
// 输出：
// array_keys
// PHP 3 >= 3.0.0
// PHP 4 >= 4.0.6
// PHP 7.4 >= 7.4.0
// PHP 8.0 => PHP 8.0.0

The above is the detailed content of How are functions in PHP libraries versioned?. For more information, please follow other related articles on the PHP Chinese website!