Constant and volatile member functions (C++ only)
A member function declared with the const
qualifier
can be called for constant and nonconstant objects. A nonconstant
member function can only be called for a nonconstant object. Similarly,
a member function declared with the volatile
qualifier
can be called for volatile and nonvolatile objects. A nonvolatile
member function can only be called for a nonvolatile object.