Can a variable be both const and volatile?

 This is possible and mostly used in embedded system.The example is Interrupt Status Register.As it is a status register , in the program we should not modify this variable.So it should be a constant.But this variable can be changed by the processor or hardware based on the interrupt condition.So when in the program ,we want to read the value of this varible , it should read the actual value with out any optimisation.For this reason ,the variable can be declared as volatile too.