Developing PHP7/8 Extensions in C++: A Comprehensive Guide for Developers

C Developing PHP7/8 Extensions: A Comprehensive Guide for Developers

Introduction:
PHP is a widely used scripting programming language, while C is a A powerful system-level programming language. By developing PHP extensions, we can combine the performance and functional advantages of C with the flexibility and ease of use of PHP. This article will provide developers with a comprehensive guide on how to develop PHP7/8 extensions using C, and provide code examples to help you get started.

1. Environment setup
Before we start developing PHP extensions, we need to set up a development environment. First, you need to install a C/C compiler such as gcc or clang. Next, you need to install the PHP development package, including header files and static libraries. You can download the corresponding version of the development package from the PHP official website. Finally, you need an integrated development environment (IDE) to assist with development work, such as Visual Studio Code or Eclipse.

2. Create a simple extension
Let us start with a simple example to understand how to create a PHP extension. Suppose we want to create a hello extension that prints "Hello, World!" in PHP.

First, create a folder named hello in your development environment and create the following files under the folder:

1. hello. c: This is the main source file of the extension and contains the implementation of the extension.
2. config.m4: This is an automated configuration file used to configure and compile extensions.
3. php_hello.h: This is the header file of the extension, which contains the declaration and definition of the extension.

In hello.c, we need to introduce the PHP header file and define our extension function. Here is a simple example:

#include "php_hello.h"

PHP_FUNCTION(hello_world)
{
    php_printf("Hello, World!
");
}

zend_function_entry hello_functions[] = {
    PHP_FE(hello_world, NULL)
    PHP_FE_END
};

zend_module_entry hello_module_entry = {
    STANDARD_MODULE_HEADER,
    "hello",
    hello_functions,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    PHP_MODULE_GLOBALS(hello),
    NULL,
    NULL,
    NULL,
    STANDARD_MODULE_PROPERTIES_EX
};

#ifdef COMPILE_DL_HELLO
ZEND_GET_MODULE(hello)
#endif

In hello.h we need to define our extension functions and modules. Here is a simple example:

#ifndef PHP_HELLO_H
#define PHP_HELLO_H

extern zend_module_entry hello_module_entry;
#define phpext_hello_ptr &hello_module_entry

#endif

In config.m4 we need to write some automation scripts to configure and compile our extension.

PHP_ARG_ENABLE(hello, whether to enable hello support,
[  --enable-hello          Enable hello support])

if test "$PHP_HELLO" != "no"; then
    PHP_SUBST(HELLO_SHARED_LIBADD)
    PHP_NEW_EXTENSION(hello, hello.c, $ext_shared)
fi

After completing the above steps, we need to enter the hello directory on the command line and execute the following commands to configure and compile our extension:

$ phpize
$ ./configure --enable-hello
$ make
$ sudo make install

Finally, in Add the following code to the PHP configuration file to load our extension:

extension=hello.so

Now, we can use the hello_world function in the PHP script to output "Hello, World!":

3. Advanced techniques for extension development
In addition to simply outputting text, PHP extensions can also interact with PHP's built-in functions and classes, using the powerful functions of C to provide PHP with more expansion capabilities. The following are some advanced tips for developing PHP extensions:

1. Support PHP type conversion:
   The type systems of PHP and C are different, so when using PHP extensions, we need to handle them well Type conversion. PHP provides some functions to facilitate type conversion, such as ZVAL_STRING(), ZVAL_LONG(), etc.
2. Support classes and objects:
   PHP supports object-oriented programming, we can define classes and instantiate objects in extensions. PHP objects can be represented by defining zval variables.
3. Support exception handling:
   PHP supports exception handling, we can throw and catch exceptions in extensions. You can use the zend_throw_exception function to throw exceptions.
4. Support callback functions:
   PHP's callback function (Callback) is a powerful mechanism. We can register callback functions in the extension and call them at the appropriate time. You can use the zend_fcall_info structure to represent the callback function.

5. Summary
Through the introduction of this article, we have learned how to use C to develop PHP7/8 extensions, and learned some advanced techniques for developing extensions. I hope this article can help developers better take advantage of C's performance and functional advantages to extend the capabilities of PHP.

Reference materials:

• PHP official website: https://www.php.net/
• PHP extension development guide: https://www.php .net/manual/en/internals2.php

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