[AccessD] Strange results with simple calculation on a form

Hi Bert-Jan

You can do that, of course, but it is preferable to solve a problem by its root.

/gustav


> Gustav,

> thanks for your answer. I keep forgetting textboxes only contain text... i
> think i will forget it this time again... ;-)
> The maximum is 2 decimals so that is no problem. But since the differences
> was at the 15th decimal (although i only tested this 1 time...) I decide to
> add round([calculation];2) in the total field. I think this is ok because i
> know only numers with 2 decimals are entered....

> Bert-Jan

> ----- Original Message ----- 
> From: "Gustav Brock" <gustav at cactus.dk>
> To: "Access Developers discussion and problem solving"
> <accessd at databaseadvisors.com>
> Sent: Thursday, March 18, 2004 11:18 AM
> Subject: Re: [AccessD] Strange results with simple calculation on a form


>> Hi Bert-Jan
>>
>> Welcome back.
>>
>> Unbound textboxes contain text no matter how you format them.
>> And decimals may not be exact Doubles and indeed not Singles.
>>
>> If you can accept a maximum of four decimals, use CCur(txtYourTextbox)
>> to convert to Currency before doing any calculation or comparison.
>> Else use CDbl() and compare to a max. tolerance of your choice:
>>
>>   If Abs(dblTotal - dblAmount) < 1E-7 Then
>>     ' Values are equal.
>>   End If
>>
>> /gustav
>>
>>
>> > Hi all,
>>
>> > i was forced to unsubscribe a while ago because i couldn't keep up with you
>> > and all the messages... ;-)
>>
>> > But today a strange thing happened i had to ask you all about. I didn't do a
>> > big search on the internet, but searched the accessd archives and didn't
>> > find it. It maybe is a well known problem, but here it goes.....
>>
>> > I have an unbound form where users will type amounts. All the txtboxes'
>> > format are set to "standard" and the decimal places is set to 2. And i check
>> > on the before_update event of these txtboxes if there are more then 2
>> > decimals, if so, cancel = true. There is an calculated total control
>> > (txtTotal) wich has a controlsource like =[txtbox1]+[txtbox2] and so on (in
>> > total 12 txtboxes)
>> > These txtboxes are used to 'split up' the amount in another txtbox.
>> > (txtAmount)
>>
>> > Before saving i check if txtAmount = txtTotal. When no decimals are used
>> > there is no problem, if there are only used decimals in 1 txtbox there is no
>> > problem. But if there are used decimals in more txtboxes access will tell me
>> > the values are not the same..... although the same values are shown... it
>> > turns out there is a difference of: 0.00000000000000710542735!!!!!!
>> > (debug.print told me this!)
>>
>> > When i use the same 'function' in VBA it works fine with the same
>> > values....????
>>
>> > So it is not a real problem, but it IS something strange... wel to me it
>> > is....
>>
>> > Thanks in advance.
>>
>> > Hope to keep up with you this time... ;-)
>>
>> > Bert-Jan