说明：  C语言变参_实现自己的printf，详细讲解变参在堆栈中的存放和读取，讲解如何实现一个变参函数，最终给出实现一个printf的参考，对于不能支持printf的系统非常有帮助，建议使用标准头文件stdarg.h。
(C language parameters _ to achieve their own printf, explain in detail on the stack in the storage and read, explain how to achieve a variable function, and finally give a printf reference, can not support the printf system is very helpful, It is recommended to use the standard header file stdarg.h.)