This section shows the ways you can use const with classes. You may want to create a local const in a class to use inside constant expressions that will be evaluated at compile time. However, the meaning of const is different inside classes, so you must understand the options in order to create const data members of a class.

You can also make an entire object const (and as you’ve just seen, the compiler always makes temporary objects const). But preserving the constness of an object is more complex. The compiler can ensure the constness of a built-in type but it cannot monitor the intricacies of a class. To guarantee the constness of a class object, the const member function is introduced: only a const member function may be called for a const object.