The C++ programming model directly supports three programming paradigms:
The procedural model as programmed in C, and, of course, supported within C++. An example of this is string manipulation using character arrays and the family of str* functions defined in the Standard C library: char boy[] = "Danny";
char *p_son;
...
p_son = new char[ strlen( boy ) + 1 ];
strcpy( p_son, boy );
...
if ( !strcmp( p_son, boy ))
take_to_disneyland( boy );
The abstract data type (ADT) model in which users of the abstraction are provided with a set of operations (the public interface), while the implementation remains hidden. An example of this is a String class: String girl = "Anna";
String daughter;
...
// String::operator=();
daughter = girl;
...
// String::operator==();
if ( girl == daughter )
take_to_disneyland( girl );
The object-oriented (OO) model in which a collection of related types are encapsulated through an abstract base class providing a common interface. An example of this is a Library_materials class from which actual subtypes such as Book, Video, Compact_Disc, Puppet, and Laptop are derived: void
check_in( Library_materials *pmat )
{
if ( pmat->late() )
pmat->fine();
pmat->check_in();
if ( Lender *plend = pmat->reserved() )
pmat->notify( plend );
}
C++ supports polymorphism through class pointers and references. This style of programming is called object-oriented.
C++ also supports a concrete ADT style of programming now called object-based (OB)—nonpolymorphic data types, such as a String class.
