CODEWITHSUNDEEP
c++c++11memoryvectorallocation
CerushDope
CerushDope

Reputation: 455

Create constant sized vector of constant sized vectors

I am trying to learn C++. Currently I ran into a tutorial, which mentioned how to create a constant sized vector like this: vector <int> v(10); Now I'm wondering how to create a constant sized vector of constant sized vectors, something like: vector <vector <int> (10)> v(10); This code doesn't work, so I wanted to ask is there a way do something like this and if there is, how?

Upvotes: 2

Views: 99

Answers (2)

songyuanyao
songyuanyao

Reputation: 172924

You could

vector<vector<int>> v(10, vector<int>(10));

i.e. construct the std::vector with 10 copies of elements with value std::vector<int>(10).

Note that for std::vector the size is not constant, it might be changed when element(s) are inserted or erased, 10 is just the initial size when v and its elements get initialized. On the other hand, the size of std::array is constant, it's specified at compile-time and can't be changed at run-time.

Upvotes: 4

Ron
Ron

Reputation: 15501

You can't have a constant sized vector of constant sized vectors without writing your own class wrapper of some kind. Use the more appropriate std::array container for the task:

std::array<std::array<int, 10>, 10> arr;

Upvotes: 3

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