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From: mullerd@prism.cs.orst.edu (Douglas Muller)
Newsgroups: comp.sys.mac.programmer
Subject: Re: This code is buggy and I don't know why, any help out there?
Message-ID: <1991Apr20.181445.17703@lynx.CS.ORST.EDU>
Date: 20 Apr 91 18:14:45 GMT
References: <8676@crash.cts.com>
Sender: @lynx.CS.ORST.EDU
Organization: Oregon State University, Computer Science Dept.
Lines: 37
Nntp-Posting-Host: prism.cs.orst.edu

In article <8676@crash.cts.com> kevin@crash.cts.com (Kevin Hill) writes:
>
> This code seems to hang the computer after moving the image for several seconds
>
>create_train()
>{
>	int			i = 0,x,y;
>	ImagePtr	train,image_ptr = first_image;
>	
>>	
>	train = (ImagePtr)NewPtr(sizeof(Image));
>	HLock(train);


	YOU NEVER LOCK POINTERS, ONLY HANDLES


>	train_image = GetResource('SICN',130);
>	HLock(train_image);
>	
	DO THE TEST BEFORE YOU LOCK THE HANDLE!

>	if (train_image == NULL)
>		ExitToShell();
>	
	THE FOLLOWING TEST SHOULD COME AFTER (train = (ImagePt)NewPtr(...)

>	if (train == NULL)
>		return;
>	
	START THERE IT IS THE MOST GLARING PROBLEM

	GOOD LUCK!
		Steve

Steve Roderick
mullerd@prism.cs.orst.edu