Parse Double Conversion

[Herb Stevenson]

Hello. I have a very large string reprentation of a number, for example
"10000010020030 040050060070080 09010". If I user Double.Parse, I get
something like 1.0000010020030 041E+33 as my output. I need to do a mod 900
conversion on this long string value (i.e. loop thru the number consistently
dividing by 900). The exponential notation seems to be causing some
precision problems as I divide.

Is there a way to have the double represnted as the entire number?

Thank you
Herb

[Nicholas Paldino [.NET/C# MVP]]

Re: Parse Double Conversion

Herb,

Unfortunately, you are using a number that can not be represented by
Decimal, and a number that is also large enough to loose precision when
stored in a double. Because of this, you will have to resort to something
else. Java had something like Number, or BigNumber, but .NET doesn't have
an equivalant. You will have to create a routine/class that can handle
this, as well as a representation for your number.

Hope this helps.


--
- Nicholas Paldino [.NET/C# MVP]
- mvp@spam.guard. caspershouse.co m

"Herb Stevenson" <tampaherb@hotm ail.com> wrote in message
news:uhByq5lTEH A.1168@TK2MSFTN GP11.phx.gbl...[color=blue]
> Hello. I have a very large string reprentation of a number, for example
> "10000010020030 040050060070080 09010". If I user Double.Parse, I get
> something like 1.0000010020030 041E+33 as my output. I need to do a mod[/color]
900[color=blue]
> conversion on this long string value (i.e. loop thru the number[/color]
consistently[color=blue]
> dividing by 900). The exponential notation seems to be causing some
> precision problems as I divide.
>
> Is there a way to have the double represnted as the entire number?
>
> Thank you
> Herb
>
>[/color]

[Jon Skeet [C# MVP]]

Re: Parse Double Conversion

Herb Stevenson <tampaherb@hotm ail.com> wrote:[color=blue]
> Hello. I have a very large string reprentation of a number, for example
> "10000010020030 040050060070080 09010". If I user Double.Parse, I get
> something like 1.0000010020030 041E+33 as my output. I need to do a mod 900
> conversion on this long string value (i.e. loop thru the number consistently
> dividing by 900). The exponential notation seems to be causing some
> precision problems as I divide.
>
> Is there a way to have the double represnted as the entire number?[/color]

You won't get precise integer values with doubles that size. You should
use the decimal type instead, so long as that's got the appropriate
range.

See http://www.pobox.com/~skeet/csharp/floatingpoint.html
and http://www.pobox.com/~skeet/csharp/decimal.html

--
Jon Skeet - <skeet@pobox.co m>

http://www.pobox.com/~skeet

If replying to the group, please do not mail me too

[Jon Skeet [C# MVP]]

Re: Parse Double Conversion

Nicholas Paldino [.NET/C# MVP] <mvp@spam.guard .caspershouse.c om> wrote:[color=blue]
> Unfortunately, you are using a number that can not be represented by
> Decimal, and a number that is also large enough to loose precision when
> stored in a double. Because of this, you will have to resort to something
> else. Java had something like Number, or BigNumber, but .NET doesn't have
> an equivalant. You will have to create a routine/class that can handle
> this, as well as a representation for your number.[/color]

Oops - I hadn't noticed that even the sample number is outside
decimal's range.

There's an implementation of BigInteger at

http://www.codeproject.com/csharp/BigInteger.asp

I haven't used it myself though.

--
Jon Skeet - <skeet@pobox.co m>

http://www.pobox.com/~skeet

If replying to the group, please do not mail me too