B: It is a pointer that defines an object, and the object is not created, so the constructor of the class is not called. There are no mistakes.
C: Data is in the private part of the class, that is, data can only be accessed through class methods, not directly through class objects. all wet
D:MyClass is a class name, not a class object. Therefore, if it wants to represent the method of a class, it needs to parse the symbol.
my class::show(); //Class name call
or
my class x(3); //Class object call
x . show();