Map (C++) Design Characteristics Key uniqueness: in map and set each key must be unique. multimap and multiset do not have this restriction.Element composition: in map and multimap each element is composed from a key and a mapped value.
In set and multiset each element is key; there are no mapped values.Element ordering: elements follow a strict weak ordering Loop through map and print all the key/value pair : map iterator « Map Multimap « C++ STL Tutorial - Map Class. Suppose that you're working with some data that has values associated with strings -- for instance, you might have student usernames and you want to assign them grades.
How would you go about storing this in C++? One option would be to write your own hash table. This will require writing a hash function and handling collisions, and lots of testing to make sure you got it right. Map. Maps are associative containers that store elements formed by a combination of a key value and a mapped value, following a specific order.
In a map, the key values are generally used to sort and uniquely identify the elements, while the mapped values store the content associated to this key. The types of key and mapped value may differ, and are grouped together in member type value_type, which is a pair type combining both: