array delete problem

[elfuz]

hi all

i'm having problem with this block of code. It seems to generate a crash and i cannot seem to find it...

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  for( u32 k = 0; k < items_.size(); k++ )
   {
	   printf("%s: %i\n",items_[k]->TexFileName,items_[k]->UsageCount);
	   if (items_[k]->UsageCount == 0)
	   {
		   if (items_[k]->Texture) {
			   items_[k]->Texture->drop();
		   }
		   delete items_[k];
		   items_.erase(k);
	   }
   } 

the array consists of the TextureManagerItem defined here:

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   array< TextureManagerItem* > items_; 

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  class TextureManagerItem
   {
   public:
      ITexture* Texture;
	  u32		TexID;
	  stringc	TexName;
	  stringc	TexFileName;
	  u32		UsageCount;
   }; 

thanks for any help

greet
elfuz

[Sylence]

don't call erase() inside the loop but call clear() after the loop. With every iteration the array becomes smaller so after you erased enough elements from the array you are trying to access elements that are no longer there.

[Metalero]

I think I had same problem in the past.

Try doing a

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k--;

below the part you erase the array item, coz remember, in this part, the array made samller, but k continue groing up.

[Bate]

You should learn how to use your debugger.

Also, make sure that the textures you drop() aren't used by Irrlicht anymore. Your program will definitely crash, if you try to remove a texture currently in use.

[elfuz]

i've tried everything however the code keeps crashing on me

i'm trying to use the debugger, however it points to crt0.c during the crash and i cannot analyze anything from the array (which i can if the crash occurs in one of my source files)

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        return __tmainCRTStartup();

[Metalero]

Use CallsStack to go back to your code (what IDE are you using ?)

[elfuz]

VC++ 2010 Express

[Nalin]

don't call erase() inside the loop but call clear() after the loop. With every iteration the array becomes smaller so after you erased enough elements from the array you are trying to access elements that are no longer there.

This is the correct idea. If you are deleting the entire array, delete all the elements then clear() the array. It makes no sense to remove each individual element from the array when you can do the same thing with a single clear().

Also, if you are trying to selectively remove multiple items from a single for loop, you will want to start at the end and work your way down, or call --k after you delete an item. The reasoning behind this is that if you delete element 0, elements 1..n will be shifted down, so element 1 becomes the new element 0. When k is incremented in the for loop, you now erase element 1, which was previously element 2. You have now skipped the old element 1, which became element 0. Walking backwards through the array solves this, as well as subtracting 1 from k when you delete an item.

[elfuz]

hmm that makes sense

thanks, i'll give that a whirl.

[ent1ty]

It all makes perfect sense