vector or map, which one to use?

Question

I\'ve heard many people say that if the number of expected elements in the container is relatively small, it is better to use std::vector instead of std::

Answer 1

Basically, maps are used for lookup.

But, sometimes std::vector can be used instead of std::map even for look up.

If there are going to be very less elements in your key-value pairs, then you can go for an iterative search using key even in std::vector<std::pair<x,y>>.

This is because of the fact that hashing takes time, especially for hashing strings and for other operations in map like storing data in heap.

You would only see a better difference in std::map, if you have more elements in which you have to lookup and also when you want to do frequent lookup in the list of elements that you have.