Editing Subtyping (section)

===C++===
The following C++ code establishes an explicit inheritance relationship between classes '''B''' and '''A''', where '''B''' is both a subclass and a subtype of '''A''', and can be used as an '''A''' wherever a '''B''' is specified (via a reference, a pointer or the object itself).

<syntaxhighlight lang=cpp>class A
{ public:
   void DoSomethingALike() const {}
};

class B : public A
{ public:
   void DoSomethingBLike() const {}
};

void UseAnA(A const& some_A)
{
   some_A.DoSomethingALike();
}

void SomeFunc()
{
   B b;
   UseAnA(b); // b can be substituted for an A.
}
</syntaxhighlight><ref name="Mitchell2002">
{{cite book
 | last=Mitchell
 | first=John
 | author-link=John C. Mitchell
 | title=Concepts in programming language
 | year=2002
 | publisher=Cambridge University Press
 | location=Cambridge, UK
 | isbn=0-521-78098-5
 | page=287
 | chapter=10 "Concepts in object-oriented languages"}}
</ref>