Why would I prefer using vector to deque

Question

Since

1. they are both contiguous memory containers;
2. feature wise, deque has almost everything vector has but more, since it is more efficient to insert

Answer 1

A deque is a sequence container which allows random access to it's elements but it is not guaranteed to have contiguous storage.

Answer 2

You woudn't prefer vector to deque acording to these test results (with source).

Of course, you should test in your app/environment, but in summary:

• push_back is basically the same for all
• insert, erase in deque are much faster than list and marginally faster than vector

Some more musings, and a note to consider circular_buffer.

Answer 3

On the one hand, vector is quite frequently just plain faster than deque. If you don't actually need all of the features of deque, use a vector.

On the other hand, sometimes you do need features which vector does not give you, in which case you must use a deque. For example, I challenge anyone to attempt to rewrite this code, without using a deque, and without enormously altering the algorithm.

Answer 4

std::deque doesn't have guaranteed continuous memory - and it's often somewhat slower for indexed access. A deque is typically implemented as a "list of vector".