listbox listcount returning negative

[crystalhelp]

I have a listbox which I populate with a resultset. My resultset brings back 428,700 rows. But when I ask for the listcount it gives me -30052. Why? The listcount works when the resultset is smaller. Is there a maximum size a listbox can handle? Thanks.

 

[TheVampire]

Standard MS Listboxes are limited to 32K ( 32768 ) individual items( essentially, the same as an integer variable ), and each item is limited to 1K in size.

Robert

 

[vb5prgrmr]

Could be wrong but I thought most controls had a limit of the type that refers to individual values, i.e. to refer to an item in a listbox it would be...

[tt]
List1.List(Integer) As String
[/tt]

and an integer in vb has a max values of -32,768 to 32,767

And try as I might I cannot find that error listed in MSDN. I remember being able to look up specific error codes and return values but for the life of me I cannot find that (-30052) error code.

I think I know why now I just tried this code
[tt]
Private Sub Form_Load()
Dim I As Double

For I = 0 To 40000
List1.AddItem I
DoEvents
Next I

MsgBox List1.ListCount

End Sub
[/tt]
and recieve a listcount of -25535

 

[strongm]

The VB listboxes are quite happy handling more items than this - as long as you use API calls to populate and interrogate them.

 

[johnwm]

A 16-bit field can either store a straight (non-signed) 16 bit integer (0 to 65535) or a signed integer ( that's 1 sign bit plus a 15 bit number (0 to 32767)).

Most VB stuff uses signed numbers, so if you overrun from 32767, the number will be displayed as a negative value.

Negative numbers are stored as 1's complements. This means that -1 returns &HFFFF, and why vb5prgrmr gets -25535 as his listcount.

&HFFFF is 65535, add the 1 to get 65536 (2^16)
40001 (actual listcount) add 25535(as displayed) gives 65536 also Let me know if this helps
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