Article:		Building a Game Engine with Cocoa, Part 2
Subject:		Incorrect Boolean login in NOTEQUAL_NSPOINTS?
Date:		2007-01-05 20:36:09
From:		Joe Jones
It would seem to me that the equation there should be p1.x != p2.x ||p1.y != p2.y. This would be the equivalent of !EQUALS_NPOINTS(p1, p2). (1,2) and (3,4) would resolve to TRUE as expected but (1,2) and (3,2) would resolve to FALSE but are obviously not equal.

Showing messages 1 through 6 of 6.

• Incorrect Boolean login in NOTEQUAL_NSPOINTS?
  2007-01-06 07:15:35  Matthew Russell | [View]
  
  
  Joe, That's a great catch. According to DeMorgan's law, you're absolutely correct. The reason this typo (from where I'd cut/pasted the previous macro) didn't surface in the execution of the program as presented is that in all cases valid NSPoints were being compared to NIL_POINT. Thus, the sub-expressions always evaluate to NO. i.e. (NO && NO == NO) and (NO || NO == NO) and it didn't make a difference as far as the end result was concerned. When you compare a valid point to another valid point, however, there would have certainly been a noticeable bug in place.
  
  Anyway, we'll have the article and project files updated shortly, along with one other small change to the opponentInLineBetweenCoord:andCoord: method . Thanks for pointing that out!
• FIXED: Incorrect Boolean login in NOTEQUAL_NSPOINTS?
  2007-01-08 08:43:30  Matthew Russell | [View]
  
  
  Just wanted to close the loop on this. Both the article and sample files have now been updated with the fix mentioned above.
  
  Looking forward to next time, where we'll finish this series off!
• FIXED: Incorrect Boolean login in NOTEQUAL_NSPOINTS?
  2007-01-12 06:52:49  wootest [View]
  
  
  I'm getting errors when building:
  
  

  [..]/BoardGame/GameBoard.h:77: error: array type has incomplete element type
  
  In file included from [..]/BoardGame/AppController.m:5:
  
  [..]/BoardGame/AppController.h:12: error: array type has incomplete element type
  
  [..]/BoardGame/AppController.m:11: error: array type has incomplete element type
  
  [..]/BoardGame/AppController.m: In function '-[AppController validLOAMovesFromSpot:withBoard:]':
  
  [..]/BoardGame/AppController.m:13: error: type of formal parameter 4 is incomplete
  
  [..]/BoardGame/AppController.m: In function '-[AppController awakeFromNib]':
  
  [..]/BoardGame/AppController.m:38: error: type of formal parameter 4 is incomplete
  
  
  
  In file included from [..]/BoardGame/GameBoard.m:7:
  
  [..]/BoardGame/GameBoard.h:77: error: array type has incomplete element type
  
  [..]/BoardGame/GameBoard.m:601: error: array type has incomplete element type

• FIXED: Incorrect Boolean login in NOTEQUAL_NSPOINTS?
  2007-01-12 17:09:37  Matthew Russell | [View]
  
  
  It appears that the zip file that contains the project has gotten corrupted. I got an error from StuffIt as well as a CRC error from "unzip" when I downloaded it, so I believe this is your problem. I've notified the folks that produce the articles and they're working to get it updated.
  
  If you want to work on this in the meantime, you should be able to take the .h and .m files given at the beginning of the article and import them into a new Xcode project, connect the outlet that's mentioned and be good to go.
  
  I'll check back in and notify everyone once the zip archive is updated on O'Reilly's server.
• FIXED: Incorrect Boolean login in NOTEQUAL_NSPOINTS?
  2007-01-15 11:23:07  Matthew Russell | [View]
  
  
  The project files are now downloadable in a non-corrupted format. Sorry about that. We're not quite sure how it happened, but it's fixed now.
  
  As for the errors mentioned about the arrays having incomplete element types, Ginkgo_52 is absolutely correct. I've been building with GCC 3.3, so I didn't notice those problems. The fix mentioned does indeed work. The only caveat I'd add is to use DIMENSION instead of hard coding 8 in those places where you have arrays defined as int[][].
  
  Anyhow, just for informational purposes, you can also go into terminal and type "sudo gcc_select 3.3" (or whatever version you want) if you want to explicitly change the default version of gcc used.
  
  I'll make these changes to the final project file for next time. Thanks again, Ginkgo_52, for the quick assist...I had initially thought that the corrupted project files might have somehow been the issue.
• FIXED: Incorrect Boolean login in NOTEQUAL_NSPOINTS?
  2007-01-15 09:55:49  Ginkgo_52 [View]
  
  
  I also receive the "array type has incomplete element type" errors when building using the GCC 4.0 compiler, but not with GCC 3.3 (the project compiles with no errors using GCC 3.3). This appears to be due to changes that were made in the GCC compiler in version 4 - the GCC compiler no longer allows incomplete (undimensioned) array types. A quick web search indicates that others have obtained this error in GCC 4.0 from code that compiled with GCC 3.x.
  
  The project will compile without errors in GCC 4.0 if the board array is explicitly dimensioned by changing the four occurrences of 'withBoard:(int[][])board' to 'withBoard:(int[8][8])board' (one each in GameBoard.h, GameBoard.m, AppController.h and AppController.m).