Introduction to Extensions
Extensions are pre-compiled codes or libraries which enable specific functions to be used in your PHP code. These extensions may be either a PHP extension or a Zend extension.We can see extensions in php.ini file.
; syntax:
; extension=modulename.extension
; For example, on Windows:
; extension=msql.dll
; under UNIX:
; extension=msql.so
Why we need to create Extensions
- To create our own efficient and high performance PHP code which adds missing features to the language.
- When there are limitations in PHP where we cannot make call to some library or OS specific calls.
- When we have our own set of intelligent business logic which we want to sell and execute but do not want this to be viewed by others.
- When we want to make PHP software to behave in a superior manner
How to create an Extension
The following system requirements need to be present to create your own PHP extensions:
- Text editor
- PHP
- Source code file and
- C compiler.
Required files:
config. m4: The first required file to store the basic configuration data used by PHP to compile your custom extension.
PHP_ARG_ENABLE(my_code,
[Whether to enable the “my_code” extension],
[-enable-my_code Enable “my_code” extension support])
if test $PHP_my_code != “no”; then // 1st argument declares the module
PHP_SUBST(my_code_SHARED_LIBADD) // 2nd tells what all files to compile
PHP_NEW_EXTENSION(my_code,my_code.c,$ext_shared) // $ext_shared is counterpart of PHP_SUBST()
fi
In this case my_code.c is source code file and its content is :
#ifdef HAVE_CONFIG_H
#include “config.h”
#endif
#include “php.h”
#define PHP_MY_CODE_VERSION “1.0”
#define PHP_MY_CODE_EXTNAME “my_code”
extern zend_module_entry my_code_module_entry;
#define phpext_my_code_ptr &my_code_module_entry
// declaration of a custom my_code_function()
PHP_FUNCTION(my_code_function);
// list of custom PHP functions provided by this extension
// set {NULL, NULL, NULL} as the last record to mark the end of list
static function_entry my_code_functions[] = {
PHP_FE(my_code_function, NULL)
{NULL, NULL, NULL}
};
// the following code creates an entry for the module and registers it with Zend.
zend_module_entry my_code_module_entry = {
#if ZEND_MODULE_API_NO >= 20010901
STANDARD_MODULE_HEADER,
#endif
PHP_MY_CODE_EXTNAME,
my_code_functions,
NULL, // name of the MINIT function or NULL if not applicable
NULL, // name of the MSHUTDOWN function or NULL if not applicable
NULL, // name of the RINIT function or NULL if not applicable
NULL, // name of the RSHUTDOWN function or NULL if not applicable
NULL, // name of the MINFO function or NULL if not applicable
#if ZEND
Add to php.ini file
The last thing you need to do is to add the following line to your php.ini to load your extension on PHP startup:
extension=my_code.so
Testing the Extension
You can test your PHP extension by typing the following command:
- $ php -r “echo my_code_function();”
