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Among the more noteworthy defect reports addressed by C++03 was the library defect report 69, [5] whose resolution added the requirement that elements in a vector are stored contiguously. [6] This codifies the common expectation that a C++ std::vector object uses a memory layout similar to an array. While most implementations satisfied this ...
For example, a container defined as std::vector<Shape*> does not work because Shape is not a class, but a template needing specialization. A container defined as std::vector<Shape<Circle>*> can only store Circles, not Squares. This is because each of the classes derived from the CRTP base class Shape is a unique type.
Added in C++26. 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 ...
Additionally, due to the lack of garbage collection in C++, programs will frequently copy an object whenever the ownership and lifetime of a single shared object would be unclear. For example, inserting an object into a standard library collection (such as a std::vector) typically involves making and inserting a copy into the collection.
In C++11, a move constructor of std::vector<T> that takes an rvalue reference to an std::vector<T> can copy the pointer to the internal C-style array out of the rvalue into the new std::vector<T>, then set the pointer inside the rvalue to null. Since the temporary will never again be used, no code will try to access the null pointer, and ...
It is implemented in the C++ standard library as forward_list. deque (double-ended queue) a vector with insertion/erase at the beginning or end in amortized constant time, however lacking some guarantees on iterator validity after altering the deque. Container adaptors queue: Provides FIFO queue interface in terms of push / pop / front / back ...
Eigen is a high-level C++ library of template headers for linear algebra, matrix and vector operations, geometrical transformations, numerical solvers and related algorithms. . Eigen is open-source software licensed under the Mozilla Public License 2.0 since version 3.1
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 ...