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[10] [11] vector<bool> does not meet the requirements for a C++ Standard Library container. For instance, a container<T>::reference must be a true lvalue of type T . This is not the case with vector<bool>::reference , which is a proxy class convertible to bool . [ 12 ]
Any class that fulfills the allocator requirements can be used as an allocator. In particular, a class A capable of allocating memory for an object of type T must provide the types A::pointer, A::const_pointer, A::reference, A::const_reference, and A::value_type for generically declaring objects and references (or pointers) to objects of type T.
Modern C++ compilers are tuned to minimize abstraction penalties arising from heavy use of the STL. The STL was created as the first library of generic algorithms and data structures for C++, with four ideas in mind: generic programming, abstractness without loss of efficiency, the Von Neumann computation model, [2] and value semantics.
Provides the class std::inplace_vector, analogous to std::vector with a fixed capacity defined at compile time. <map> Provides the container class templates std::map and std::multimap, sorted associative array and multimap. <mdspan> Added in C++23. Provides the class template std::mdspan, analogous to std::span but the view is multidimensional ...
For example, the template base class in the Factorial example below is implemented by matching 0 rather than with an inequality test, which was previously unavailable. However, the arrival in C++11 of standard library features such as std::conditional has provided another, more flexible way to handle conditional template instantiation.
Delayed evaluation solves this problem, and can be implemented in C++ by letting operator+ return an object of an auxiliary type, say VecSum, that represents the unevaluated sum of two Vecs, or a vector with a VecSum, etc. Larger expressions then effectively build expression trees that are evaluated only when assigned to an actual Vec variable ...
In C++ pointers to non-static members of a class can be defined. If a class C has a member T a then &C::a is a pointer to the member a of type T C::*. This member can be an object or a function. [16] They can be used on the right-hand side of operators .* and ->* to access the corresponding member.
One same container type can have more than one associated iterator type; for instance the std::vector<T> container type allows traversal either using (raw) pointers to its elements (of type *<T>), or values of a special type std::vector<T>::iterator, and yet another type is provided for "reverse iterators", whose operations are defined in such ...