An unsigned type is a data type that does not represent negative numbers, but only positive numbers.

Unsigned is usually added before the data type keyword.

Unsigned data types mainly include the following categories:

Unsigned char // unsigned character type, the range of numbers that can be represented is 0 ~ (2 8-1).

Unsigned int // unsigned integer, the range of numbers that can be represented is 0 ~ (2 16- 1).

Unsigned long int // unsigned long type, the range of numbers that can be represented is 0 ~ (2 16- 1).