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Jun 23, 2009 · In the programming world, polymorphism is used to make applications more modular and extensible. Instead of messy conditional statements describing different courses of action, you create interchangeable objects that you select based on your needs. That is the basic goal of polymorphism. edited Oct 13, 2016 at 13:17.
May 2, 2011 · 66.8k 91 234 326. 31. Actually, C++ has four kinds of polymorphism: parametric (genericity via templates in C++), inclusion (subtyping via virtual methods in C++), overloading and coercion (implicit conversions). Conceptionally, there is little distinction between function overloading and operator overloading. – fredoverflow.
Mar 6, 2010 · Virtual Functions are used to support Runtime Polymorphism. That is, virtual keyword tells the compiler not to make the decision (of function binding) at compile time, rather postpone it for runtime". You can make a function virtual by preceding the keyword virtual in its base class declaration. For example, class Base.
Bar* temp = new Bar(container); Or of course you could make Bar or its constructor a template as Kornel has shown. If you actually want some type-safe compile-time polymorphism, you could use Boost.TypeTraits is_base_of or some equivalent: template<class T>. Bar::Bar(const Container<T>& c) {.
Oct 29, 2014 · Polymorphism works just fine with both references and pointers. Share. Improve this answer. Follow ...
Apr 17, 2014 · ptr = new C; f(*ptr); delete ptr; ptr = NULL; #endif. } Since f accepts a reference, polymorphic is maintained even though you're feeding it a A. Typically you'd actually invoke a member function through ptr, using virtual dispatch to ensure that the correct code is executed: std::unique_ptr<A> ptr;
Jan 9, 2010 · Some compilers support this feature as an option which is disabled by default. This must be enabled for runtime type checking using dynamic_cast to work properly. Virtual Functions are responsible for Run-time Polymorphism in C++. A class that has at least one virtual function has polymorphic type.
Apr 21, 2013 · The underlying problem is that to have a polymorphic type the compiler doesn't know how big the subclasses are going to be, so you can't just have a vector of the base type, as it won't have the extra space needed by subclasses. For this reason you will need to use pass-by-reference semantics as described above.
Dec 5, 2012 · In C++, polymorphism and arrays don't mix. Since in general the size of the derived class is different to the size of the base class, polymorphism and pointer arithmetic don't play together nicely. Since array access involves pointer arithmetic, expressions such as pBase[1] don't work as expected.
Dec 10, 2009 · 26. Way back when, "compile time polymorphism" meant function overloading. It applies only to functions because they're all you can overload. In current C++, templates change that. Neil Butterworth has already given one example. Another uses template specialization. For example: #include <iostream>. #include <string>.
