C++ STL: Vector vs Deque

What are the main differences between vector and deque in C++ STL?

Vectors are dynamic arrays that allow fast random access, while deques are double-ended queues that allow fast insertions and deletions at both ends.

When should I use a deque instead of a vector?

Use a deque when you need efficient insertions or deletions at both ends, while vectors are better for random access.

Are there any performance considerations I should be aware of?

Yes, vectors have better cache locality and are generally faster for random access, while deques may have overhead due to their structure.

Can you give an example of when to choose one over the other?

If you're implementing a queue where you frequently add and remove elements from both ends, use a deque. For a list where you mostly access elements by index, use a vector.