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dynamic_cast is a keyword to cast
data types in the same inheritance hierarchy, for example
an Animal to a Monkey.
There are two types of dynamic_cast:
-
From a derived class to a base class (for example, from a Monkey to an Animal):
this is called an upcast and will always succeed (as every Monkey is an Animal)
-
From a base class to a derived class (for example, from an Animal to a Monkey):
this is called a downcast and will not always succeed (as not every Animal is a Monkey). If a
downcast cannot succeed, dynamic_cast returns
an empty pointer
It is not possible to use dynamic_cast on smart pointers, use
boost::dynamic_pointer_cast instead.
-
Use dynamic_cast where class hierarchy navigation is unavoidable [1]
-
Use dynamic_cast for type-safe explicit navigation of a class hierarchy [2]
-
Use dynamic_cast to a reference type when failure to find the required class is considered a failure [3]
-
Use dynamic_cast to a reference type when failure to find the required class is considered a valid alternative [4]
-
Prefer virtual functions to repeated switch-statements based on typeid or dynamic_cast [5]
- Bjarne Stroustrup. The C++ Programming Language (4th edition). 2013. ISBN: 978-0-321-56384-2. Chapter 22.7. Advice. page 663: '[2] Use dynamic_cast where class hierarchy navigation is unavoidable'
- Bjarne Stroustrup. The C++ Programming Language (4th edition). 2013. ISBN: 978-0-321-56384-2. Chapter 22.7. Advice. page 663: '[3] Use dynamic_cast for type-safe explicit navigation of a class hierarchy'
- Bjarne Stroustrup. The C++ Programming Language (4th edition). 2013. ISBN: 978-0-321-56384-2. Chapter 22.7. Advice. page 663: '[4] Use dynamic_cast to a reference type when failure to find the required class is considered a failure'
- Bjarne Stroustrup. The C++ Programming Language (4th edition). 2013. ISBN: 978-0-321-56384-2. Chapter 22.7. Advice. page 663: '[5] Use dynamic_cast to a reference type when failure to find the required class is considered a valid alternative'
- Bjarne Stroustrup. The C++ Programming Language (4th edition). 2013. ISBN: 978-0-321-56384-2. Chapter 22.7. Advice. page 663: '[10] Prefer virtual functions to repeated switch-statements based on typeid or dynamic_cast'
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