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// Declares a map iterator std:: map < Key, Value >:: iterator it; ... Below is an example of looping through a map to display all keys and values using iterators:
In the programming language C++, unordered associative containers are a group of class templates in the C++ Standard Library that implement hash table variants. Being templates, they can be used to store arbitrary elements, such as integers or custom classes.
Although std::map is typically implemented using a self-balancing binary search tree, C++11 defines a second map called std::unordered_map, which has the algorithmic characteristics of a hash table. This is a common vendor extension to the Standard Template Library (STL) as well, usually called hash_map , available from such implementations as ...
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, a vector would have a random-access iterator, but a list only a bidirectional iterator. Iterators are the major feature that allow the generality of the STL. For example, an algorithm to reverse a sequence can be implemented using bidirectional iterators, and then the same implementation can be used on lists, vectors and deques.
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 ...
Associative arrays may also include other operations such as determining the number of mappings or constructing an iterator to loop over all the mappings. For such operations, the order in which the mappings are returned is usually implementation-defined.
The erase–remove idiom cannot be used for containers that return const_iterator (e.g.: set) [6] std::remove and/or std::remove_if do not maintain elements that are removed (unlike std::partition, std::stable_partition). Thus, erase–remove can only be used with containers holding elements with full value semantics without incurring resource ...