What is the performance of unordered_map in C++11?

What is the performance of unordered_map in C++11?

The unordered_map in C++11 offers average constant time complexity for insertions, deletions, and lookups.

How does it compare to std::map?

Unlike std::map, which is implemented as a balanced tree and has logarithmic time complexity, unordered_map uses a hash table.

Are there any downsides to using unordered_map?

Yes, unordered_map can have higher memory usage due to its hash table structure and may suffer from performance degradation if many collisions occur.

When should I prefer unordered_map over std::map?

You should prefer unordered_map when you need fast access and don't require the elements to be sorted.