PHP CALLBACK FUNCTIONS
- A callback function (often referred to as just "callback") is a function which is passed as an argument into another function.
- Any existing function can be used as a callback function.
- To use a function as a callback function, pass a string containing the name of the function as the argument of another function.
- A callback is a function passed as an argument to another function.
- This technique allows a function to call another function.
- A callback function can run after another function has finished.
TYPES OF CALLBACK FUNCTIONS IN PHP :
- Simple callback.
- Static class method call
- Object method callback.
- Callback using a Closure.
RETURNING A CALLBACK IN PHP :
- In returning a callback, the called function returns a callback instead of executing it immediately.
- The calling code where the callback is returned can execute the returned callback immediately, pass it to some other function and so on.
EXAMPLE FOR CALLBACK FUNCTIONS IN PHP :
<?php
//Function to callback
function my_callback_function()
//Function to callback
function my_callback_function()
{
echo 'Hello, Rosa!';
}
//PASS my_callback_function INTO call_user_func()
call_user_func('my_callback_function');
?>
echo 'Hello, Rosa!';
}
//PASS my_callback_function INTO call_user_func()
call_user_func('my_callback_function');
?>
Output :
Hello, Rosa!
