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When program is executed, six elements are inserted using the insert() function, then the first element is deleted using erase() function and the size of the map is outputted. Next, the user is prompted for a key to search for in the map. Using the iterator created earlier, the find() function searches for an element with the given key. If it ...
The member function erase can be used to delete an element from a collection, but for containers which are based on an array, such as vector, all elements after the deleted element have to be moved forward to avoid "gaps" in the collection. Calling erase multiple times on the same container generates much overhead from moving the elements.
The containers are defined in headers named after the names of the containers, e.g., unordered_set is defined in header <unordered_set>. All containers satisfy the requirements of the Container concept , which means they have begin() , end() , size() , max_size() , empty() , and swap() methods.
The STL provides a set of common classes for C++, such as containers and associative arrays, that can be used with any built-in type or user-defined type that supports some elementary operations (such as copying and assignment). STL algorithms are independent of containers, which significantly reduces the complexity of the library.
Name Description <array> Added in C++11 and TR1. Provides the container class template std::array, a container for a fixed sized array. <bitset> Provides the specialized container class std::bitset, a bit array. <deque> Provides the container class template std::deque, a double-ended queue. <flat_map> Added in C++23.
Similarly, a delete expression calls a delete function, also known as a deallocator function, whose name is operator delete. [2] [3] Any new expression that uses the placement syntax is a placement new expression, and any operator new or operator delete function that takes more than the mandatory first parameter (std:: size_t) is a placement ...
This requests a memory buffer from the free store that is large enough to hold a contiguous array of N objects of type T, and calls the default constructor on each element of the array. Memory allocated with the new[] must be deallocated with the delete[] operator, rather than delete. Using the inappropriate form results in undefined behavior ...
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.