说明：  linux环境下，我们一般借助printf打印醒目的字符方便程序调试，但是当程序调试通过以后发布时，有又不得不删掉这些打印语句。 示例代码中利用宏定义#define 解决了上述问题。
(In linux, we generally debug a program by using "printf" fuction to print eye-catching character. But later when the program needs to be released, we have to delete the "printf" statements. Sample code solves the above problem, using#define macros )