如果之前未接触过，很难把握对于返回值为指针的函数如何调用，本例以主函数调用一个返回值为指针的函数为例，很好的演示了这一问题-If you have not previously exposed to, it is difficult to grasp how to call the function return value is a pointer to this case, the main function calls a function return value is a pointer, for example, a good demonstration of the problem