how to rearrange index of RPointerArray?

[slinx]

hi, I need to do random addition and deletion from array and will store pointers in the array. Now I am using RPointerArray for the purpose. Is there any method to re-arrange array index after deletion an item from the array. let's say I have 4 items in the array ( 0,1,2,3) now item 2 is deleted from the array ( 0,1,3). Is there any method to rearrange array index to (0,1,2) .Or is there any other data structure suitable for the purpose? Thanks

[vineet.jain]

I think the array re-organizes itself when an element is removed from it(RPointerArray's ,Remove() method does that i suppose).

[symbianyucca]

it does indeed reduce the indexes after deletion, so if you have experienced problems with it, you might want to share the code sample which is not working as expected.

[wizard_hu_]

(Just a minor remark: you still need the delete for the pointed object, RPointerArray::Remove removes the pointer only

delete iArray[i];
iArray.Remove(i);

)

[slinx]

Thanks vineet.jain and symbianyucca for reply. My code looks as follows

RPointerArray<CMyObject> iPtrArr;
CMyObject* iMyObj;

void RemoveObject(TInt index)
{
	CMyObject* obj = iPtrArr.operator [](index);
	iPtrArr.Remove(index);
	delete obj;
	obj = NULL;

	iPtrArr.Compress();
		
}



void GetObject(TInt index)
{	
	
	if(index<iPtrArr.Count)
		CMyObject* obj = iPtrArr.operator [](index);
	if(obj)
	{
	   iMyObj = obj;
	}
}

I am sometimes getting KERN-EXEC 3 while using above codes.I have to randomly add and remove objects from the array.It may happen that array has 4 items ( 0,1,2,3 ), now item 1 is deleted and then GetObject is called with index 1. what will happen in that case?
thanks

[symbianyucca]

you might also add if(index<iPtrArr.Count && index >=0), so you would not get -1 as an index.

Basically if you delete index 1, then your original index 2 will be at index 1

[slinx]

(Just a minor remark: you still need the delete for the pointed object, RPointerArray::Remove removes the pointer only

delete iArray[i];
iArray.Remove(i);

)

Thanks wizard_hu_. Will it not do the same task?

CMyObject* obj = iPtrArr.operator [](index);
iPtrArr.Remove(index);
delete obj;
obj = NULL;

[wizard_hu_]

Effectively yes. However I have to say I like my coding style more. 2 lines vs. 4 lines, no dummy variables involved. Also, operators are exactly invented for making code more readable. iPtrArr.operator[](index) vs. iPtrArr[index]...

[slinx]

Basically if you delete index 1, then your original index 2 will be at index 1

Thanks symbianyucca. That is what I need to know, need to figure out why getting KERN-EXC 3 on some cases.

[symbianyucca]

Thanks symbianyucca. That is what I need to know, need to figure out why getting KERN-EXC 3 on some cases.

if you first try that one, and then you could also check that you are not adding invalid pointers to the array in the beginning..

[duncan.waugh]

-The null dereference could be happening in the following sequence:

1) GetObject(indexX);
2) RemoveObject(indexX);
3) Then you access iMyObj

Probably worth checking iMyObj against the pointer you delete in RemoveObject() and setting it to null if they are equal.

- Alternatively GetObject() looks a little iffy. Heap pointers are not null initialised, if the index passed in is out of bounds what is "obj" initialised to in your current code?