Using Rounding on a Double

[Danny Woolston]

Hi

I have a double that i want to round to a certain number of decimal places
this is the code i use

Return Math.Round(mdNu mber, mbDecimalPlaces )

mbDecimalPlaces is the number of decimal places that i want, but it doesn't
use them with two decimal places i still get 0.0 or 9.9

Any ideas?
--
Kind Regards

Danny Woolston

[Jonathan Amend]

You could use the ([number]).ToString([number formatting expression]) like
so:

Dim TestNumber as Double = 1.2345
Dim strNumber as String
strNumber = TestNumber.ToSt ring("#.00000")
'strNumber = "1.23450"
strNumber = TestNumber.ToSt ring("#.00")
'strNumber = "1.23"
strNumber = TestNumber.ToSt ring("00.#")
'strNumber = "01.2345"

"Jon Skeet" <sk***@pobox.co m> wrote in message
news:MP******** *************** *@news.microsof t.com...

Danny Woolston <da************ *@farmade.com> wrote:

I have a property of a control which will return a double, but the control allows the user to return a number of decimal places.

So if the decimal places are set to 2 and the number stored is 1.021 then on a call to the number property i want returned 1.02, or if the the number
stored is 1.3 and a decimal place of 3 then i want returned 1.300.

Let me stress that this is number only property i cannot use the format
property of the string.

Well you've got to - because doubles themselves don't *have* a number
of decimal places, they just have values. You can round a double to the
extent that rounding 1.021 to 2DP will round it to the closest double
value to 1.02, but there's no difference in the double itself between
1.5 and 1.50.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet/
If replying to the group, please do not mail me too

[Danny Woolston]

Hi

Thanks for the reply, but i need the number as a double not a string

--
Kind Regards

Danny Woolston
Software Developer

"Jonathan Amend" <ce*******@hotm ail.com> wrote in message
news:3f15f0db$1 _2@aeinews....

You could use the ([number]).ToString([number formatting expression]) like
so:

Dim TestNumber as Double = 1.2345
Dim strNumber as String
strNumber = TestNumber.ToSt ring("#.00000")
'strNumber = "1.23450"
strNumber = TestNumber.ToSt ring("#.00")
'strNumber = "1.23"
strNumber = TestNumber.ToSt ring("00.#")
'strNumber = "01.2345"

"Jon Skeet" <sk***@pobox.co m> wrote in message
news:MP******** *************** *@news.microsof t.com...

Danny Woolston <da************ *@farmade.com> wrote:

I have a property of a control which will return a double, but the control allows the user to return a number of decimal places.

So if the decimal places are set to 2 and the number stored is 1.021 then on a call to the number property i want returned 1.02, or if the the number stored is 1.3 and a decimal place of 3 then i want returned 1.300.

Let me stress that this is number only property i cannot use the format property of the string.

Well you've got to - because doubles themselves don't *have* a number
of decimal places, they just have values. You can round a double to the
extent that rounding 1.021 to 2DP will round it to the closest double
value to 1.02, but there's no difference in the double itself between
1.5 and 1.50.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet/
If replying to the group, please do not mail me too

[Anthony Moore]

If you have .Net V1.1 you can try using the Decimal class. Unlike Double,
it does consider trailing decimal places as significant. It can also store
more data than Double and the precision for decimal number does not drop
off. However, it is bigger and slower than Double (16 bytes vs 8 bytes).

V1.0 did not support this feature on Double. It was changed to comply with
the new ECMA standard.