# Function Handling Functions

## Introduction

These functions all handle various operations involved in working with functions.

## Requirements

No external libraries are needed to build this extension.

## Installation

There is no installation needed to use these functions; they are part of the PHP core.

## Runtime Configuration

This extension has no configuration directives defined in php.ini.

## Predefined Constants

This extension has no constants defined.

## Table of Contents

- call_user_func_array — Call a user function given with an array of parameters
- call_user_func — Call a user function given by the first parameter
- create_function — Create an anonymous (lambda-style) function
- func_get_arg — Return an item from the argument list
- func_get_args — Returns an array comprising a function's argument list
- func_num_args — Returns the number of arguments passed to the function
- function_exists — Return TRUE if the given function has been defined
- get_defined_functions — Returns an array of all defined functions
- register_shutdown_function — Register a function for execution on shutdown
- register_tick_function — Register a function for execution on each tick
- unregister_tick_function — De-register a function for execution on each tick