The pointer address range of C language is 4 bytes, from address 0x00000000~ to address 0xFFFFFFFF. However, some fields are protected by the system or the hardware platform used does not exist at all, so the user pointer cannot fully use this space. But users don't have to worry, as long as the pointer is used according to the specification, the system will automatically arrange it correctly.

C language is a general computer programming language, which is widely used. The design goal of C language is to provide a programming language that can compile and process low-level memory in a simple way, generate a small amount of machine code and run without any support of running environment.

Although C language provides many low-level processing functions, it still maintains good cross-platform characteristics. C language programs written in standard specifications can be compiled on many computer platforms, even including some embedded processors (single chip microcomputer or MCU) and supercomputers.

In 1980s, in order to avoid the differences of C language grammars used by different developers, the American National Bureau of Standards formulated a complete set of international standard grammars of C language, called ANSI C, as the original standard of C language.