What is Increament or decrement operator?

They are (++) increment operator in c.
(--)decrement operator in c.
These two operators are called unary operator as they require only one operand.The operand should be a variable not a constant.

* (++) operator :- Add one to the value of operand.
*(--) operator :- substract one to the value of operand.

# These operators are used in two form
1 pastfix form
2 prefix form