How to find curves in reverse direction?

[highend3djojan-]

A specific number of curves needs to be created in-between selected curves of the same vertex count and degree (for creating Hair, man). Created the code BUT issues if some curves are in reverse direction. So we need to find which all are the curves to reverse/rebuild, then reverse, and then apply my code. But HOW can we find the "problematic" curves?
My Qn is: How to find the curves in reverse direction with the other "majority" curves?

[joojaa]

Its impossibe to answer as you dont tell us how you consider the curves to be the rioght way around. So what spatial relationship defines correct way around?

[nowayfra]

Its surely no bulletproof approach and depends on that your adjacent curves dont differ to much in their shape but you could do a check if the start of neighbour curves approximately aim into the same direction. Get the tangent vector of each curve at start parameter, then get the angles between them. If they are less than 90 degrees, they probably aim into the same dircetion, otherwise you would do a reverse. You also could take the different distances of start and end cvs into account. As i said, thats surely not a bulletproof thing.