2. Unsigned integer

An integer is used to represent a whole number, one that does not have any fractional part. There are two types of integers in computing - unsigned and signed.

Unsigned integers are the simplest to think about, but can only deal with positive numbers. For example, the unsigned 8 bit binary integer

                          1111 1111

is the equivalent of denary 255.

If the software is only going to deal with positive numbers then this is a very efficient data type to use.

For example, pixel colour can be represented with three positive 8 bit integers - one for Red, one for Green and one for Blue - there are no negative values to be handled.

Many computer languages support two sizes of unsigned integer.

Short unsigned integer

This is 16 bits wide ( 2 bytes) which means it can efficiently handle any positive number up to $2^{16} - 1$ which is 65,535. In binary the largest short unsigned integer is

                     1111 1111 1111 1111

In a typical computer language ('C' for example) a variable of short integer type may be specifically declared like this

                     short int MyVariable

or the language uses short integer by default, like this

                    int MyVariable

Long unsigned integer

This is 32 bits wide (4 bytes) which means it can handle any positive number up to 4.29 billion or $2^{32} - 1$ to be exact. Long unsigned int is suited to handling very large positve whole numbers.

The disadvantage of using long integer is that it consumes 4 bytes of storage, which is wasteful if all the numbers being used are below 65,535.

Typical use for the long int is as the data type for an auto-incrementing primary key in a database as this can handle more than sixty five thousand records.

In a typical computer language, it may be fully declared like this

                   unsigned long int MyVariable