Question

I have a vector of events, with the first one being a guard for easier computations. I have implemented a reset operation as follows:

void reset()
{
    myVector.resize(1);
}

so that only the first one element remains. Does this operation reallocate memory? I will call it in a loop, so I would like it to be very time-efficient. If it does, then what would be an efficient alternative?

Answer 1

Does this operation reallocate memory?

If there are no elements in the vector, then the first call to resize(1); will do the allocation. Otherwise, no.

what would be an efficient alternative?

The efficient alternative is to assign the vector with enough space during it’s construction. Then you are sure no reallocation is going to happen.