STL vectors with uninitialized storage?
- by Jim Hunziker
I'm writing an inner loop that needs to place structs in contiguous storage. I don't know how many of these structs there will be ahead of time. My problem is that STL's vector initializes its values to 0, so no matter what I do, I incur the cost of the initialization plus the cost of setting the struct's members to their values.
Is there any way to prevent the initialization, or is there an STL-like container out there with resizeable contiguous storage and uninitialized elements?
(I'm certain that this part of the code needs to be optimized, and I'm certain that the initialization is a significant cost.)
Also, see my comments below for a clarification about when the initialization occurs.
SOME CODE:
void GetsCalledALot(int* data1, int* data2, int count) {
int mvSize = memberVector.size()
memberVector.resize(mvSize + count); // causes 0-initialization
for (int i = 0; i < count; ++i) {
memberVector[mvSize + i].d1 = data1[i];
memberVector[mvSize + i].d2 = data2[i];
}
}
