18.1) Const Methods
Methods that don’t modify the object in any way should always be declared as const
. Declaring them as such means that they can be called on const
instances of your class. If you don't declare a method as const
then subsequently create a const
instance in a program and attempt to call the method on it, you will get a compiler error.
The const
declaration should be used in both the header and implementation files. Thus, the header file defining the Rectangle
class changes to this:
class Rectangle { public: Rectangle(int, int, int, int); int get_x() const; int get_y() const; ... };
And the method implementations now look like this:
int Rectangle::get_x() const { return corner_x; } int Rectangle::get_y() const { return corner_y; } ...