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.