It is stipulated in the standard that the int type must be 16 or higher, and the long type must be 32 bits. In the past, when using a 16 bit computer, these two kinds of data were a 16 bit and a 32 bit. But after entering the x86 era, both of them are actually 32 bits. Int type is generally consistent with the number of processor bits, representing the addressing space of two memories.

There are three kinds of integer variables: int, long int and short int, in which two bytes are used to store integers, short int is one byte and long int is four bytes.