前面简单介绍了用C语言实现PHP扩展的步骤，见用C开发PHP扩展的步骤，那个是扩展一个函数，这里讲述一下如何用C扩展类。

    准备实现的类如下：

class Rectangle{
	private $_width;
	private $_height;
	public function __construct($width, $height){
		$this->_width = $width;
		$this->_height = $height;
	}
	public function clone(){
		return new Rectangle($this->_width, $this->_height);
	}
	public function setWidth($width){
		$this->_width = $width;
	}
	public function setHeight($height){
		$this->_height = $height;
	}
	public function getWidth(){
		return $this->_width;
	}
	public function getHeight(){
		return $this->_height;
	}
	public function getArea(){
		return $this->_width * $this->_height;
	}
	public function getCircle(){
		return ($this->_width + $this->_height) * 2;
	}
}

实现类扩展的步骤如下：（首先下载PHP源码，这里使用的是php-5.2.8）

1，建立扩展骨架

cd php-5.2.8/ext
./ext_skel --extname=class_ext

cd php-5.2.8/ext/class_ext
vi config.m4

[   --enable-class_ext       Enable class_ext support])两行前面的dnl，修改后为：

dnl Otherwise use enable:  
PHP_ARG_ENABLE(class_ext, whether to enable class_ext support,  
dnl Make sure that the comment is aligned:  
[  --enable-class_ext           Enable class_ext support])

cd php-5.2.8/ext/class_ext
vi php_class_ext.h
#在 PHP_FUNCTION(confirm_class_ext_compiled); 后面增加申明函数;

PHP_METHOD(Rectangle,__construct);
PHP_METHOD(Rectangle,clone);
PHP_METHOD(Rectangle,setWidth);
PHP_METHOD(Rectangle,setHeight);
PHP_METHOD(Rectangle,getWidth);
PHP_METHOD(Rectangle,getHeight);
PHP_METHOD(Rectangle,getArea);
PHP_METHDO(Rectangle,getCircle);

vi class_ext.c
#申明方法的参数，注册到函数表中

ZEND_BEGIN_ARG_INFO(arg_construct,2)
ZEND_ARG_INFO(0, width)
ZEND_ARG_INFO(0, height)
ZEND_END_ARG_INFO()

ZEND_BEGIN_ARG_INFO(arg_set_width,1)
ZEND_ARG_INFO(0, width)
ZEND_END_ARG_INFO()

ZEND_BEGIN_ARG_INFO(arg_set_height,1)
ZEND_ARG_INFO(0, height)
ZEND_END_ARG_INFO()

const zend_function_entry class_ext_functions[] = {
    PHP_FE(confirm_class_ext_compiled, NULL)
    PHP_ME(Rectangle, __construct, arg_construct, ZEND_ACC_CTOR|ZEND_ACC_PUBLIC)
    PHP_ME(Rectangle, clone, NULL, ZEND_ACC_PUBLIC)
    PHP_ME(Rectangle, setWidth, NULL, ZEND_ACC_PUBLIC)
    PHP_ME(Rectangle, setHeight, NULL, ZEND_ACC_PUBLIC)
    PHP_ME(Rectangle, getWidth, NULL, ZEND_ACC_PUBLIC)
    PHP_ME(Rectangle, getHeight, NULL, ZEND_ACC_PUBLIC)
    PHP_ME(Rectangle, getArea, NULL, ZEND_ACC_PUBLIC)
    PHP_ME(Rectangle, getCircle, NULL, ZEND_ACC_PUBLIC)
    {NULL, NULL, NULL}  /* Must be the last line in class_ext_functions[] */
};

#其中ZEND_ACC_CTOR表示构造函数，ZEND_ACC_PUBLIC表示访问权限为PUBLIC。

#接下来，在模块初始化函数中注册并初始化类

zend_class_entry *Rectangle_ce; //zend内部类结构变量
PHP_MINIT_FUNCTION(class_ext)
{
    zend_class_entry Rectangle;
    INIT_CLASS_ENTRY(Rectanble, "Rectangle", class_ext_functions); //第二个参数为类名，第三个参数为类的函数列表
    Rectangle_ce = zend_register_internal_class_ex(&Rectangle, NULL, NULL TSRMLS_CC); //注册类
    zend_declare_property_null(Rectangle_ce, ZEND_STRL("_width"), ZEND_ACC_PRIVATE TSRMLS_CC); //初始化类的属性_width
    zend_declare_property_null(Rectangle_ce, ZEND_STRL("_height"), ZEND_ACC_PRIVATE TSRMLS_CC);  //初始化类的属性_height
    return SUCCESS;
}

#在文件最后增加类的成员函数的具体实现代码