Essential skills for developing PHP7/8 extensions: C++ detailed tutorial

Essential skills for developing PHP7/8 extensions: C Detailed tutorial

Introduction:
With the development of PHP language, extension development in the PHP ecosystem plays a vital role. C is one of the main languages ​​for PHP extension development. This article will introduce in detail the necessary skills for developing PHP7/8 extensions: C. We will start with the basic knowledge of C and gradually guide readers to understand how to write PHP extensions in C, with code examples.

Part One: C Basics
C is a high-level programming language widely used in system development and low-level programming. Before you start learning C, make sure you have a grasp of basic programming concepts and syntax.

1. Classes and Objects
   C is an object-oriented programming language, and classes are one of the most basic concepts in C. A class defines the properties and behavior of an object. The following is a simple class definition example:

class MyClass {
public:
    int myFunction();
private:
    int myProperty;
};

2. Inheritance and Polymorphism
   C supports the concepts of inheritance and polymorphism. Inheritance allows the creation of a new class that inherits the properties and behavior of another class. Polymorphism allows using a pointer to a base class to call methods of a derived class. The following is an example of inheritance and polymorphism:

class Base {
public:
    virtual void myFunction() {
        cout << "This is the base class" << endl;
    }
};

class Derived : public Base {
public:
    void myFunction() override {
        cout << "This is the derived class" << endl;
    }
};

3. Pointers and references
   In C, pointers and references are very important concepts. A pointer is a variable that stores the memory address of another variable. A reference is an alias for a variable. The following are examples of pointers and references:

int myVariable = 10;
int* myPointer = &myVariable; // 指针
int& myReference = myVariable; // 引用

Part 2: C Interaction with PHP
C extensions interact with PHP by using PHP's C API. The following are some commonly used C API functions:

1. Initialization extension and module definition
   When writing an extension, you need to implement an initialization function in the C code and register the module in the PHP extension. The sample code is as follows:

// 扩展初始化函数
zend_module_entry myextension_module_entry = {
    STANDARD_MODULE_HEADER,
    "myextension",
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    STANDARD_MODULE_PROPERTIES_EX
};

// 注册扩展模块
#ifdef COMPILE_DL_MYEXTENSION
ZEND_GET_MODULE(myextension)
#endif

2. Define PHP function
   Function defined in C can be registered as a PHP callable function through the C API function. The sample code is as follows:

ZEND_FUNCTION(my_php_function) {
    // 函数实现代码
    php_printf("Hello from my PHP function!
");
}

3. Return value, parameters and exception handling
   In the C extension, you can use the C API function to process the parameters and return value of the function and throw exceptions. The sample code is as follows:

ZEND_FUNCTION(my_php_function) {
    zval* param1;
    ZEND_PARSE_PARAMETERS_START(1, 1)
        Z_PARAM_ZVAL(param1)
    ZEND_PARSE_PARAMETERS_END();

    // 参数处理
    if (Z_TYPE_P(param1) != IS_STRING) {
        zend_throw_exception(NULL, "Invalid argument provided", 0);
        return;
    }

    // 返回值处理
    RETURN_STRING(Z_STRVAL_P(param1));
}

Part 3: C extension example
The following is a simple C extension example, which defines a PHP function my_extension_hello(), accept A string parameter and print it to PHP's output:

#include "php.h"

ZEND_FUNCTION(my_extension_hello) {
    zval* param;
    ZEND_PARSE_PARAMETERS_START(1, 1)
        Z_PARAM_ZVAL(param)
    ZEND_PARSE_PARAMETERS_END();

    if (Z_TYPE_P(param) != IS_STRING) {
        zend_throw_exception(NULL, "Invalid argument provided", 0);
        return;
    }

    php_printf("Hello, %s!
", Z_STRVAL_P(param));

    RETURN_TRUE;
}

ZEND_BEGIN_ARG_INFO(arginfo_my_extension_hello, 0)
    ZEND_ARG_INFO(0, name)
ZEND_END_ARG_INFO()

static const zend_function_entry my_extension_functions[] = {
    ZEND_FE(my_extension_hello, arginfo_my_extension_hello)
    ZEND_FE_END
};

zend_module_entry my_extension_module_entry = {
    STANDARD_MODULE_HEADER,
    "myextension",
    my_extension_functions,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    STANDARD_MODULE_PROPERTIES_EX
};

#ifdef COMPILE_DL_MYEXTENSION
ZEND_GET_MODULE(myextension)
#endif

Summary:
This article briefly introduces the necessary skills for developing PHP7/8 extensions: C. We start from the basic knowledge of C, gradually guide readers to understand how to write PHP extensions in C, and provide code examples. I hope this article can help developers better understand and master the skills of C extension development, and contribute to the development of the PHP ecosystem. For more in-depth C and PHP extension development content, readers are recommended to further refer to official documentation and other related materials.

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