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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. The STL and the C++ Standard Library are two distinct entities. [3]
The Boost C++ Libraries provide a dynamic_bitset class [4] whose size is specified at run-time. The D programming language provides bit arrays in its standard library, Phobos, in std.bitmanip. As in C++, the [] operator does not return a reference, since individual bits are not directly addressable on most hardware, but instead returns a bool.
The C++ Standard Library is based upon conventions introduced by the Standard Template Library (STL), and has been influenced by research in generic programming and developers of the STL such as Alexander Stepanov and Meng Lee. [4] [5] Although the C++ Standard Library and the STL share many features, neither is a strict superset of the other.
In C++20, a new header <bit> was added, containing functions std::popcount and std::has_single_bit, taking arguments of unsigned integer types. In Java, the growable bit-array data structure BitSet has a BitSet.cardinality() method that counts the number of bits that are set.
In C++, associative containers are a group of class templates in the standard library of the C++ programming language that implement ordered associative arrays. [1] Being templates , they can be used to store arbitrary elements, such as integers or custom classes.
Unlike other STL containers, such as deques and lists, vectors allow the user to denote an initial capacity for the container. Vectors allow random access ; that is, an element of a vector may be referenced in the same manner as elements of arrays (by array indices).
Bit fields can be used to reduce memory consumption when a program requires a number of integer variables which always will have low values. For example, in many systems, storing an integer value requires two bytes (16-bits) of memory; sometimes the values to be stored actually need only one or two bits.
In adapting STL to be included in the C++ Standard Library, Stepanov worked closely with several members of the standards committee, including Andrew Koenig and Bjarne Stroustrup, who observed that custom allocators could potentially be used to implement persistent storage STL containers, which Stepanov at the time considered an "important and ...