Data storage (1)

C Language type ：1. Built in type

Basic classification of types ： integer ——char,short,int,long

                          floating-point ——float,double

                          Construction type —— An array type , Type of structure （struct), Enumeration type (enmu), Joint type (union)

                          Pointer types ——int *pi,char *pa,float* pf,void* pv

                          Empty type ——void Indicates empty type （ No type ）

                    2. Custom type

The meaning of type ：1. Use this type to open up the size of the space （ Size determines the range of use ）

                    2. How to look at the perspective of memory space

Big end, small end ： Big end （ Storage ） Pattern , The low bit of data is stored in the high address of memory , And the high end of the data , Stored in a low address in memory

                The small end （ Storage ） Pattern , The low bit of data is stored in the low address of memory , And the high end of the data , Stored in a high address in memory

Why is there a big end and small end mode ？ This is because in a computer system , We are in bytes , Each address unit corresponds to this byte , A byte is 8bit. But in c In language, except 8bit Of char outside , also 16bit Of short type ,32bit Of long type . in addition , For digits greater than 8 Bit processor , for example 16 Bits or 32 Bit processor , Because the register width is larger than one byte , So there must be a problem of how to arrange multiple bytes , This leads to the big end storage mode and the small end storage mode