C++11: Using Unordered Map vs Map

What are the main differences between unordered_map and map in C++11?

The main differences are in their underlying data structures: unordered_map uses a hash table, while map uses a balanced tree. This affects performance and ordering.

When should I use unordered_map instead of map?

You should use unordered_map when you need faster average-case lookups and don't require the elements to be in any specific order.

Are there any drawbacks to using unordered_map?

Yes, unordered_map can have higher memory usage due to its hash table implementation, and worst-case lookup time can be O(n) if many collisions occur.

Can you give an example of when to use each?

Sure! Use map when you need sorted keys, like in a priority queue. Use unordered_map for fast access, like counting occurrences of elements.