C++ Multimap Features Explained

In C++, multimap is an associative container that allows storing key-value pairs and allows keys to be repeated. The functionalities of multimap are as follows:

1. Allow storage of key-value pairs, with the possibility of duplicate keys.
2. A series of member functions are provided for inserting, deleting, and searching elements.
3. Support the functionality of sorting by key value, you can use a custom comparison function to specify the sorting rules.
4. Support for iterators allows for traversing the elements in a container.
5. The member function count() has been provided for finding the number of elements with a specific key value.
6. The member functions lower_bound() and upper_bound() have been provided to search for the range of elements with a specific key value.
7. The member function equal_range() is provided to obtain the range of elements with a specific key value.
8. The member function erase() is provided to delete elements with specific key values.
9. Supports multiple operator overloads, such as ==, !=, <, etc.
10. The member function size() is provided to retrieve the number of elements in the container.