PHP Callback Functions
PHP Callback Functions
In PHP, a callback function is a function that can be passed as a parameter to another function, and then executed within that function. Callback functions are commonly used in event-driven programming, where the callback function is executed when a certain event occurs.
Here’s an example of a callback function in PHP:
function my_callback($param) {
echo "The parameter is: " . $param;
}
function my_function($callback, $param) {
$callback($param);
}
my_function("my_callback", "Hello, world!");
In this example, we define a callback function my_callback() that takes a single parameter and echoes it to the screen. We then define another function my_function() that takes two parameters: a callback function and a parameter to pass to the callback function. Within my_function(), we call the callback function with the provided parameter using the $callback() syntax.
Finally, we call my_function() and pass it the name of the my_callback() function and the string “Hello, world!” as the parameter. This causes my_function() to execute my_callback() with the provided parameter, resulting in the output “The parameter is: Hello, world!”.
Callback functions are very flexible and can be used for a wide variety of purposes in PHP programming. They can be used to implement custom validation or filtering logic, execute code in response to events, or implement complex algorithms that require multiple levels of function nesting.