Delicious Bookmark this on Delicious Share on Facebook SlashdotSlashdot It! Digg! Digg

PHP : Function Reference : Function Handling Functions

Function Handling Functions


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


No external libraries are needed to build this extension.


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

Code Examples / Notes » ref.funchand


You can do some kind of overloading functions in PHP using "function_exists".
Let's suppose you want a script to call plugins that are php files and you want the plugins to "override" behaviours that if not overriden are used by default.
You might for example write a "mySQL table viewer" which displays a table and it "opens a table", "dumps the header", "dumps row-by-row" and then "closes the table".
Let's suppose you want a plugin for "Stocks" which prints negative stocks in red, so you want to override the "dumping row-by-row" to do that behaviour. Instead you do not want to have all the "default behaviour" repeated in the plugin.
You may then do the following:
1) Define a default plugin (ex: "default.php"
2) Write all your functions in default.php to open, dump and close, but add them a suffix:
3) Call your functions with a wrapper: Insetad of this:
open_table() or open_table_default() write this:
4) Then write a function called plugincall which uses function_exists() to see if you call one or the other function:
function plugincall($desired_function_name)
if( function_exists( $desired_function_name))
   //Call the plugin
   //Note the $ before the name
 $desired_function_name = $desired_function_name . "_default";
 if( function_exists($desired_function_name))
     //Call the default
     //Note the $ before the name
     // Nor the plugin nor the default were defined
So, now, if the require_once(plugin.php) contains a function called "open_table()", it will be used. Instaed, "open_table_default()" will be used.
It's not like overloading functions, but it is very useful to write scripts ampliable by other programmers: If they write a function, it is used, if not, the default is used.
See ya!
Xavier Montero.


Xavier's example is rather complicated, and his task would be much more simply accomplished by using classes. Define a base class to do the basic functions open, dump, and close, and create extension classes to override whatever behavior.
class foo {
 function open() {
   // Default functionality for open()
 function dump() {
   // Default functionality for dump()
 function close() {
   // Default functionality for close()
class bar extends foo {
 function open() {
   // Override functionality of open()
 // dump() and close() remain as in class foo

michael dot bommarito

I've developed an easy-to-use hack using these functions to emulate overloaded functions.  It's especially handy for constructors and/or C++ style templating.
Here's a little example to get you going.  This does the trick for most circumstances, and if you need more intelligent parsing, it's not too hard to implement with regex or a more suitable classification scheme.
N.B. Note the lack of whitespace between variable types in case strings.
class Matrix {
function Matrix() {
 $args = func_get_args();
 $argmatch = implode(",", array_map('gettype', $args));
 switch( $argmatch ) {
   case 'integer,integer':
     //initialize m x n matrix
   case 'integer,integer,integer':
     //initialize m x n matrix with constant c
   case 'integer,integer,float':
     //initialize m x n matrix with constant c
   case 'array':
     //initialize from array (2D....)
   case 'array,integer':
     //intialize from array (1D packed with m rows)
     //(void) overload?
     //error handling?

michael t. mcgrew

An interesting way to use functions is by putting other things than PHP in them, i.e. HTML CSS. This can be useful if you will be using a format for many pages. Yes, the include function can be used also, but by defining them in functions can make them more portable in a way and keep you from having to make many include files. You could use include() when one will be putting big portions of PHP, HTML, and/or CSS and will be using them in many pages. Then you could use PHP, HTML, and/or CSS in a function when it is smaller portions of code and only want it to be on a few pages.
I have been using include() for HTML and CSS in my early days of PHP coding, but I will be using functions for that a lot more now.
<?php function a() {  ?>
<style type="text/css">
table {
border: 1px dashed black;
background: #95EAFE;
.linkbar {
<?php }  ?>
Now doing:
<?php a(); ?>
will return all of the CSS just as if you had wrote it on the actual page, or used include() . The same thing goes for HTML code inside a function. The possibilities are endless...

Change Language

Follow Navioo On Twitter
.NET Functions
Apache-specific Functions
Alternative PHP Cache
Advanced PHP debugger
Array Functions
Aspell functions [deprecated]
BBCode Functions
BCMath Arbitrary Precision Mathematics Functions
PHP bytecode Compiler
Bzip2 Compression Functions
Calendar Functions
CCVS API Functions [deprecated]
Class/Object Functions
Classkit Functions
ClibPDF Functions [deprecated]
COM and .Net (Windows)
Crack Functions
Character Type Functions
Cybercash Payment Functions
Credit Mutuel CyberMUT functions
Cyrus IMAP administration Functions
Date and Time Functions
DB++ Functions
Database (dbm-style) Abstraction Layer Functions
dBase Functions
DBM Functions [deprecated]
dbx Functions
Direct IO Functions
Directory Functions
DOM Functions
DOM XML Functions
enchant Functions
Error Handling and Logging Functions
Exif Functions
Expect Functions
File Alteration Monitor Functions
Forms Data Format Functions
Fileinfo Functions
filePro Functions
Filesystem Functions
Filter Functions
Firebird/InterBase Functions
Firebird/Interbase Functions (PDO_FIREBIRD)
FriBiDi Functions
FrontBase Functions
FTP Functions
Function Handling Functions
GeoIP Functions
Gettext Functions
GMP Functions
gnupg Functions
Haru PDF Functions
hash Functions
Hyperwave Functions
Hyperwave API Functions
i18n Functions
IBM Functions (PDO_IBM)
iconv Functions
ID3 Functions
IIS Administration Functions
Image Functions
Imagick Image Library
Informix Functions
Informix Functions (PDO_INFORMIX)
Ingres II Functions
IRC Gateway Functions
PHP / Java Integration
JSON Functions
LDAP Functions
libxml Functions
Lotus Notes Functions
LZF Functions
Mail Functions
Mailparse Functions
Mathematical Functions
MaxDB PHP Extension
MCAL Functions
Mcrypt Encryption Functions
MCVE (Monetra) Payment Functions
Memcache Functions
Mhash Functions
Mimetype Functions
Ming functions for Flash
Miscellaneous Functions
mnoGoSearch Functions
Microsoft SQL Server Functions
Microsoft SQL Server and Sybase Functions (PDO_DBLIB)
Mohawk Software Session Handler Functions
mSQL Functions
Multibyte String Functions
muscat Functions
MySQL Functions
MySQL Functions (PDO_MYSQL)
MySQL Improved Extension
Ncurses Terminal Screen Control Functions
Network Functions
Newt Functions
NSAPI-specific Functions
Object Aggregation/Composition Functions
Object property and method call overloading
Oracle Functions
ODBC Functions (Unified)
ODBC and DB2 Functions (PDO_ODBC)
OpenAL Audio Bindings
OpenSSL Functions
Oracle Functions [deprecated]
Oracle Functions (PDO_OCI)
Output Control Functions
Ovrimos SQL Functions
Paradox File Access
Parsekit Functions
Process Control Functions
Regular Expression Functions (Perl-Compatible)
PDF Functions
PDO Functions
Phar archive stream and classes
PHP Options&Information
POSIX Functions
Regular Expression Functions (POSIX Extended)
PostgreSQL Functions
PostgreSQL Functions (PDO_PGSQL)
Printer Functions
Program Execution Functions
PostScript document creation
Pspell Functions
qtdom Functions
Rar Functions
GNU Readline
GNU Recode Functions
RPM Header Reading Functions
runkit Functions
SAM - Simple Asynchronous Messaging
Satellite CORBA client extension [deprecated]
SCA Functions
SDO Functions
SDO XML Data Access Service Functions
SDO Relational Data Access Service Functions
SESAM Database Functions
PostgreSQL Session Save Handler
Session Handling Functions
Shared Memory Functions
SimpleXML functions
SNMP Functions
SOAP Functions
Socket Functions
Standard PHP Library (SPL) Functions
SQLite Functions
SQLite Functions (PDO_SQLITE)
Secure Shell2 Functions
Statistics Functions
Stream Functions
String Functions
Subversion Functions
Shockwave Flash Functions
Swish Functions
Sybase Functions
TCP Wrappers Functions
Tidy Functions
Tokenizer Functions
Unicode Functions
URL Functions
Variable Handling Functions
Verisign Payflow Pro Functions
vpopmail Functions
W32api Functions
WDDX Functions
win32ps Functions
win32service Functions
xattr Functions
xdiff Functions
XML Parser Functions
XML-RPC Functions
XMLReader functions
XMLWriter Functions
XSL functions
XSLT Functions
YAZ Functions
YP/NIS Functions
Zip File Functions
Zlib Compression Functions
eXTReMe Tracker