Getting input directly into a vector in C++

Question

Consider the following code piece:

...
int N,var;
vector nums;
cin >> N;
while (N--)
{
   cin >> var;
   nums.push_back(var);
}
...
         


        

Answer 1

vector nums(N);
for (int i = 0; i < N; i++)
{
    cin >> nums[i];
}

In the general case, this is actually more efficient. Calling std::vector::push_back() repeatedly without an initial reserve will lead to lots of reallocations.