介绍C语言指针的四方面的内容：指针的类型、指针所指向的类型、指针的值或者叫指针所指向的内存区、指针本身所占据的内存区,和指针的应用-Describes four aspects of pointers in C content: the type of pointer, pointer types, pointer value or name of the memory area pointer, the pointer memory area occupied by itself, and the application of the pointer