C++ Hash Table vs Map: What's the Difference?

What is the difference between a hash table and a map in C++?

In C++, a hash table is typically implemented using unordered_map, while a map is implemented using ordered_map. The main difference is that hash tables provide average constant time complexity for lookups, while maps provide logarithmic time complexity.

When should I use a hash table instead of a map?

You should use a hash table when you need fast access and don't require order. If you need to maintain order, use a map.

Are there any downsides to using hash tables?

Yes, hash tables can have issues with collisions, which can degrade performance. They also use more memory compared to maps.

Can you give an example of when to use each?

Sure! Use a hash table for a fast lookup of user IDs, while a map is better for storing sorted data like a phone book.