The difference between vector and deque

c++ c++11 vector deque
rajenpandit picture rajenpandit · Feb 27, 2014 · Viewed 28.6k times · Source

As vector and deque both provides a function to push_back the element at the last.

where deque also provides a function push_front to insert the element at the beginning, which is bit costly in case of vector.

My question is when we can achieve the same functionality (push_back) of vector by using deque, then why vector is required?

Answer

paxdiablo picture paxdiablo · Feb 27, 2014

One main difference between vectors and deques is that the latter allows efficient insertion at the front of the structure as well as the back.

Deques also do not guarantee that their elements are contiguous in memory so the at-style operator (indexing) may not be as efficient.

Note that the difference is unlikely to matter in practice for smaller collections but would generally become more important if, for example, the collection size increases or you're modifying it many times per second.

Related questions

How do I pass multiple ints into a vector at once?

Currently when I have to use vector.push_back() multiple times. The code I'm currently using is std::vector<int> TestVector; TestVector.push_back(2); TestVector.push_back(5); TestVector.push_back(8); TestVector.push_back(11); TestVector.push_back(14); Is there …

Read More
Obtaining list of keys and values from unordered_map

What is the most efficient way of obtaining lists (as a vector) of the keys and values from an unordered_map? For concreteness, suppose the map in question is a unordered_map<string, double>. I'd then like to …

Read More
Removing item from vector, while in C++11 range 'for' loop?

I have a vector of IInventory*, and I am looping through the list using C++11 range for, to do stuff with each one. After doing some stuff with one, I may want to remove it from the list and delete …

Read More