Constant volatile variable declaration is possible or not? if give any one example and reason.
yes, constant variable declaration is possible. Constants can be defined by placing the keyword const in front of any variable declaration. If the keyword volatile is placed after const, then this allows external routines to modify the variable.
Example: An input-only buffer for an external device could be declared as const volatile to make sure the compiler knows that the variable should not be changed and that its value may be altered by processes other than the current program.