Reputation: 47
I have a question on C++ move semantics in 2D vector (or a vector of vectors). It comes from a problem of dynamic programing. For simplicity, I just take a simplified version as the example.
//suppose I need to maintain a 2D vector of int with size 5 for the result.
vector<vector<int>> result = vector<vector<int>>(5);
for(int i = 0; i < 10; i++){
vector<vector<int>> tmp = vector<vector<int>>(5);
//Make some updates on tmp with the help of result 2D vector
/*
Do something
*/
//At the end of this iteration, I would like to assign the result by tmp to prepare for next iteration.
// 1) The first choice is to make a copy assignment, but it might introduce some unnecessary copy
// result = tmp;
// or
// 2) The second choice is to use move semantics, but I not sure if it is correct on a 2D vector.
// I am sure it should be OK if both tmp the result are simply vector (1D).
// result = move(tmp);
}
So, is it OK to simply use `result = move(tmp);' for the move semantics of 2D vector?
Upvotes: 0
Views: 522
Reputation: 61
Yes, because result is not '2D' vector, it's simply 1-D vector of vectors.
Upvotes: 1