Build a Basic PHP Extension: Step‑by‑Step Guide

In this article we introduce how to create a basic PHP extension, covering environment setup, the extension skeleton, and the core PHP kernel data structures and APIs involved.

Creating a simple PHP extension is straightforward: you only need to create a few files. You can do this manually or generate the skeleton using the ext_skel.php script.

<code>$ php php-src/ext/ext_skel.php --ext test --dir .</code>

The script is available only in the PHP source distribution, not in binary builds. It creates a directory test containing the extension framework files.

<code>$ cd test
$ ls
config.m4 config.w32 php_test.h test.c tests</code>

The generated files have the following roles:

config.m4 : configuration script used by phpize or buildconf to add extension options to the configure command.

config.w32 : Windows‑specific configuration file (will be discussed later).

php_test.h : C header that defines common extension macros; optional for single‑file extensions but useful for multi‑file projects.

test.c : main source file implementing the extension, defining internal functions, classes, and constants.

tests : directory for PHP test scripts (covered in later sections).

These are the essential components of a PHP extension skeleton. The next step is to build and install the extension.

Feel free to leave comments or questions below.