1, basic type: the type specifier is int, accounting for 4 bytes in memory (there may be differences between different systems, here it was originally 2, verified as 4 in windows system, and so was VAX system), and its value is a basic integer constant.

2. Short integer: the type specifier is short int or short' c110f1. For different compilation systems, the range of bytes and values occupied will be different.

3. long integer: the type specifier is long int or Long, which takes up 4 bytes of memory and its value is a long integer constant.

4. Unsigned type: The type specifier is unsigned. In compiling system, signed number and unsigned number are distinguished by how to interpret most significant bit in bytes. If most significant bit is interpreted as a data bit, integer data is represented as an unsigned number.

Extended data:

Various unsigned types occupy the same number of bytes in memory space as the corresponding signed types. However, because the sign bit is omitted, it cannot represent a negative number. The following table lists the number of memory bytes allocated by various integer quantities in Turbo C and the representation range of this number.

Defining a variable means allocating a corresponding size of storage space for the variable in memory, and at the same time determining the storage mode and possible operations of the variable value.

Baidu Encyclopedia-Integer Variable