Chapter Summary

C++ provides several specialized facilities that are tailored to particular kinds of problems.

Customized memory management is used by classes in two ways: A class may need to define its own internal memory allocation that allows it to streamline allocation of its own data members. A class might want to define its own, class-specific operator new and operator delete functions that will be used whenever new objects of the class type are allocated.

Some programs need to directly interrogate the dynamic type of an object at run time. Run-time type identification (RTTI) provides language level support for this kind of programming. RTTI applies only to classes that define virtual functions; type information for types that do not define virtual functions is available but reflects the static type.

Pointers to ordinary objects are typed. When we define a pointer to a class member, the pointer type must also encapsulate the type of the class to which the pointer points. A pointer to member may be bound to any member of the class that has the same type. When we dereference a pointer to member, an object from which to fetch the member must be specified.

C++ defines several additional aggregate types:

• Nested classes, which are classes defined in the scope of another class. Such classes are often defined as implementation classes of its enclosing class.

• Unions are a special kind of class that may contain only simple data members. An object of a union type may define a value for only one of its data members at any one time. Unions are most often nested inside another class type.

• Local classes, which are very simple classes defined local to a function. All members of a local class must be defined in the class body. There are no static data members of a local class.

C++ also supports several inherently nonportable features including bit-fields and volatile, which make it easier to interface to hardware, and linkage directives, which make it easier to interface to programs written in other langauges.