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C++ fully supports C pointers and C typecasting. It also supports a new group of typecasting operators to help catch some unintended dangerous casts at compile-time. Since C++11, the C++ standard library also provides smart pointers (unique_ptr, shared_ptr and weak_ptr) which can be used in some situations as a safer alternative to primitive C ...
The following is a declaration of the concept "equality_comparable" from the <concepts> header of a C++20 standard library. This concept is satisfied by any type T such that for lvalues a and b of type T, the expressions a==b and a!=b as well as the reverse b==a and b!=a compile, and their results are convertible to a type that satisfies the concept "boolean-testable":
For this purpose, the C++11 standard library defines the smart pointer classes std::unique_ptr for single-owned objects and std::shared_ptr for objects with shared ownership. Similar classes are also available through std::auto_ptr in C++98, and boost::shared_ptr in the Boost libraries. Also, messages can be sent to network resources using RAII.
There was a proposal to add concepts as an explicit language feature in C++11, though it was rejected as "not ready". C++20 eventually accepted the refined design of concept. Concepts are an example of structural typing. As generics in Java and C# have some similarities to C++'s templates, the role of concepts there is played by interfaces ...
The C++ examples in this section demonstrate the principle of using composition and interfaces to achieve code reuse and polymorphism. Due to the C++ language not having a dedicated keyword to declare interfaces, the following C++ example uses inheritance from a pure abstract base class .
By including, in the class definition, one or more abstract methods (called pure virtual functions in C++), which the class is declared to accept as part of its protocol, but for which no implementation is provided. By inheriting from an abstract type, and not overriding all missing features necessary to complete the class definition. In other ...
With the advent of C++11 the rule of three can be broadened to the rule of five (also known as "the rule of the big five" [5]) as C++11 implements move semantics, [6] allowing destination objects to grab (or steal) data from temporary objects. The following example also shows the new moving members: move constructor and move assignment operator.
A class in C++ is a user-defined type or data structure declared with any of the keywords class, struct or union (the first two are collectively referred to as non-union classes) that has data and functions (also called member variables and member functions) as its members whose access is governed by the three access specifiers private, protected or public.