How to make a move ordering system?

[manfromfms]

Well i understand that it has to guess which move is better but how do i make it sort faster? I tried to make function for ordering but it was soooo slow

[stone50]

You could use the OrderByDescending method. The way I'm doing it, I have a struct to contain a move and an associated evaluation.

struct MoveEval
{
   public Move Move;
   public float Eval;
}

Then I sort them like this:

// Assume that GetMoveEvals() returns an Enumerable of type MoveEval
MoveEval[] sortedMoveEvals = GetMoveEvals().OrderByDescending(moveEval => moveEval.Eval).ToArray();

[manfromfms]

Well it is slow. Maybe sth is wrong with my code but it seems to be working worse than without any sorts at all

[WhiteMouse1]

How do you measure the slowness?

[manfromfms]

Seconds per move

[mcthouacbb]

Take a look at the CPW page for move ordering and The rustic page for move ordering
Actually, go ahead and read everything on the second site since it's very helpful. It has a lot of techniques that are difficult to find elsewhere or aren't explicitly mentioned.

[mcthouacbb]

Also, if you try to order captures, make sure you use MVV_LVA(unless you have a different algorithm that takes into account the rest of the board, such as Static Exchange Evaluation. It might see counterintuitive, but Rook takes rook should be searched before pawn takes bishop. A lot of research has gone into move ordering in chess.