PHP functions used to work with functions

This tutorial will show you some important functions that can be used to work with your own written PHP functions.

Let’s start:

call_user_func(“func”, arg)
Calls the function “func” with the given argument “arg”.

<?php function func($arg1, $arg2) { return "$arg1 - $arg2"; } echo call_user_func("func", '2', '1'); echo call_user_func(function($arg) { echo "Tutorial $arg"; }, 'php'); ?>

It will return 2-1 and the second call of call_use_func may be used only with PHP 5.3+ and is a more advanced way to use it. The output would be ‘Tutorial php’.

call_user_func_array(“func”, array_arg)

<?php function func1($arg1, $arg2) { return $arg1 + $arg2; } $func2 = function($arg1, $arg2) { return $arg1 * $arg2; }; $aray_p = array(4, 3); echo call_user_func_array("func1", $aray_p); echo call_user_func_array($func2, $aray_p); ?>

The first function is defined normally and in $array_p we are storing the number 7 and 8, their sum will be 7.
The second function is stored in $func2 variable. The result will be 12.

create_function(“arguments”, “function_code”)
Creates a function that has the “arguments” and the “function code”; it returns the function or FALSE.

<?php $var = create_function('$arg', 'return $arg*2;'); echo $var(4); ?>

In $var we are creating the function which takes one argument: $arg and the code: return $arg * 2, so the result of the call will be 8.

func_num_args()
Returns the number of the arguments which are taken by the function. It is used inside the function.

<?php function mytest() { $nr_args = func_num_args(); echo "Numar argumente primite: $nr_args"; } mytest(4, 1, 'php'); ?>

The number of arguments is 3.

func_get_args()
Returns an array with the arguments received by the function. It is used inside that function.

<?php function mytest() { $array_args = func_get_args(); print_r($array_args); } mytest(3, 'tutorial', 'www.example.com'); ?>

register_shutdown_function(“func”, param1, param2 …)
Makes “func” to run after the script is executed or if exit() is called. param1, param2 … are optional and will be attached to the function.

<?php function end_script() { echo 'Terminare script'; } register_shutdown_function("end_script"); echo (2+3).' - '; ?>

For more information please visit: PHP.net

That’s it! I hope you enjoy reading this PHP tutorial.