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In PHP, preg_replace_callback_array is a very useful function for batch replacement of strings based on a set of patterns and callback functions. This function is especially efficient when dealing with multiple regular expressions, allowing developers to use different callback functions in one operation to match and replace the content of multiple patterns. This article will explain to programming beginners the concept of preg_replace_callback_array and its usage methods.
The preg_replace_callback_array function is one of the functions in PHP used to perform regular expression replacement. Unlike the traditional preg_replace function, preg_replace_callback_array allows you to specify different callback functions for different regular expression patterns. This makes it more flexible and efficient when dealing with complex text replacements.
preg_replace_callback_array(array $patterns_and_callbacks, string $subject): string|false
$patterns_and_callbacks : This is an associative array where each key is a regular expression pattern and each value is a callback function. The callback function will receive the matching substring and process it according to the logic.
$subject : This is the input string to perform the replacement operation.
Return value: Returns the replaced string. If an error occurs, it returns false .
The preg_replace_callback_array function will iterate through each pattern you pass and call the corresponding callback function for each match. The callback function will usually receive an array of matching results, allowing you to perform any custom processing of matching results. The function then replaces the return value of the callback function.
Suppose we have a string that needs to perform different replacement operations on the date and email address:
<?php
// Strings to be processed
$subject = "Please contact me：email@m66.net or 2025-04-21";
// Define replacement patterns and callback functions
$patterns_and_callbacks = [
'/\d{4}-\d{2}-\d{2}/' => function($matches) {
return "date：" . $matches[0];
},
'/[a-zA-Z0-9._%+-]+@m66\.net/' => function($matches) {
return "This is a legal email address：" . $matches[0];
}
];
// Perform a replacement
$result = preg_replace_callback_array($patterns_and_callbacks, $subject);
// Output result
echo $result;
?>
Please contact me：This is a legal email address：email@m66.net or date：2025-04-21
In this example, preg_replace_callback_array calls two callback functions according to different modes. The first callback function is responsible for handling date formats, while the second callback function is responsible for handling email addresses. This is a typical usage of preg_replace_callback_array .
The core of the callback function is to process the matching results. In the above example, the callback function receives an array containing matching string information. You can modify or process this information as needed in the callback function.
One of the biggest advantages of using preg_replace_callback_array is that it allows you to specify different callback functions for different modes, which makes the code more modular and maintainable. Assuming that there are many different patterns of strings you need to process, you can easily write independent callback logic for each pattern without making complex conditional judgments within a callback function.
Pattern order : preg_replace_callback_array processes each pattern in order of the array, so you want to make sure the pattern order is appropriate.
Performance : Although preg_replace_callback_array is convenient, if you want to deal with a large amount of text and patterns, it may have a certain performance overhead. Therefore, appropriate optimization should be carried out in scenarios where high performance requirements are required.
preg_replace_callback_array is a powerful PHP function that allows you to specify different callback functions for multiple regular expressions, thereby implementing complex text replacement. In this way, you can handle multiple modes of replacement operations more clearly and flexibly, especially when you need to deal with complex text. I hope this article can help you understand the concept and usage of preg_replace_callback_array !
