OpenChess

Hello,
I make an AI I made a lot of game on lichess.com ( about 150 ) I have never encountered any problem ( illegal move ) I have 2000 elo on lichess but when I run a PerfT I obtain theses results :
1 : 20
2 : 400
3 : 8,902
4 : 197,281
5 : 4,865,867 <- problem should be 4,865,609 ( 4,865,609 + 258 en passant = 4,865,867 ?? )
6 : 119,072,421 <- problem should be 119,060,324

To determine legal move I make the move and if the king is check then I remove the move from list move
I implemented en passant, castling ( with rules ), promotions ...
I would like to know if there are several test which can isolate some probably problem
Thank you

There are perft tests with things like 'divide' built into them that allow you to itemize.

Here is a thread about perft + divide. Stockfish will do this for you, so if you implement it for your engine, you can track down the branches that fail more easily.
http://www.talkchess.com/forum/viewtopi ... vide+perft

Here is a thread on debugging perft:
http://www.talkchess.com/forum/viewtopi ... vide+perft

Here is a place to get divide perft lists for huge trees:
http://talkchess.com/forum/viewtopic.ph ... ght=divide

Thank you for your link , I used JetChess on your first link and I have been able to divide and determine my problem. I generate 2x each move En passant because of an "if" instead of "else if" so now I obtain the right result now
Thank you