如果你看this documentation,第一个参数只返回Zend扩展.
与PHP(“简单”)扩展相比,什么是Zend扩展？
解决方法:
Zend扩展程序挂钩到语言的“较低级别”.单个扩展也可以是PHP扩展和Zend扩展.例如,Xdebug使用Zend扩展组件挂接到语言的较低层以拦截调试调用.
Zend扩展是Zend Engine(ZE)本身的扩展,它是PHP堆栈的最低级别.
The PHP Wiki提供了许多其他信息.我将引用介绍：
As you should kNow, we distinguish between “PHP extensions” and “Zend extensions”. Consider this vocabulary to follow the article, as internally, the sources prefer talking about PHP extensions as “modules” and Zend extensions as “extensions”. We’ll keep the more clear “PHP extension” vs “Zend extension” wordings.
Both extension kinds share lots of stuff. The difference between both types is mainly in hooks they register into the Engine. Remember that, despite it is very uncommon, an extension can be both a PHP extension and a Zend extension at the same time. Xdebug is a good example.
Zend扩展也会在加载PHP扩展之前加载.
一个示例PHP扩展是PHP Redis Extension.这是一个仅限PHP的扩展,并不直接挂钩到Zend引擎.
