OpenEuphoria

RE: Deleting List Items

• Posted by Derek Parnell <Derek.Parnell at SYD.RABOBANK.COM> Aug 01, 2002
• 351 views

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Hi Robert,
> 
> I am looking for help with list views, particularly with 
> deleting items.  My 
> list are small (1-10 items)
> 
> Here is my original code:
> 
> for x = 1 to getCount(LV) do
>    VOID = deleteItem(LV, x)
> end for
>
> This works most of the time, 

I guess you are trying to delete all the items. This method will not work.
Here's why...

Let's say you have a list with 4 item in it. Thus the code is equivalent to:

   for x = 1 to 4 do:
      VOID = deleteItem(LV, x)
   end for

and this is equivalent to:

   VOID = deleteItem(LV, 1)
   VOID = deleteItem(LV, 2)
   VOID = deleteItem(LV, 3)
   VOID = deleteItem(LV, 4)

Now the parameter passed to deleteItem is the Row Number you wish to delete.
So after the first deleteItem() here the list will contain three rows. After
the second deleteItem() it will contain two rows. The third deleteItem() is
then going to try to delete Row #3 in a list that now only contains two
rows. Thus it fails to delete it.

There are four ways (at least) to delete all rows. The easiest is :

  eraseItems(LV)

The next easiest is :

  deleteItem(LV, -1)

If you need to do a loop, then either of these will work:

   for x = 1 to getCount(LV) do
       deleteItem(LV, 1) -- Always delete the top row.
   end for

or :

   for x = getCount(LV) to 1 by -1 do
       deleteItem(LV, x) -- Always delete the current bottom row.
   end for


>so I have implemented an addition...
> 
> while getCount(LV) > 0 do
>    for x = 1 to getCount(LV) do
>       VOID = deleteItem(LV, x)
>    end for
> end while
> 
> This seems to be better, but sometimes send the program into 
> a seemingly 
> infinite loop that it can not break free from.  

I don't understand why this doesn't work. I'll investigate a bit further. It
is a slow way to do it though.

-------------
cheers,
Derek.

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