Day 1 - My class

Today I must write a class.
I will call it MyClass.
It should have a member called a and it will be of char type.
char is enough.
Its value shouldnt and will never be higher then 100 an less then -100. So it OK.
Member function calc which recalculate member a.
Other member functions for access and cheanging member a are implied. There are not worth mentioning.
It looks something like this

 class MyClass
    MyClass( char P_a ): M_a(P_a){}

	void clac(){std::cout << "Do not disturb! calc in progress ..." << std::endl; }

    char a;