Wrong result with double.Parse()

[schlied]

Hello,

i have the following problem in our project:
If I try to parse a string value with the following line
double x = double.Parse("39.95238", CultureInfo.InvariantCulture);
x contains 39.9523799999.... instead of the correct one.
What could be the reason for that?

Thanks in advance

Chris

[=?ISO-8859-1?Q?Lasse_V=E5gs=E6ther_Karlsen?=]

sc*****@gmail.com wrote:

Hello,

i have the following problem in our project:
If I try to parse a string value with the following line
double x = double.Parse("39.95238", CultureInfo.InvariantCulture);
x contains 39.9523799999.... instead of the correct one.
What could be the reason for that?

Thanks in advance

Chris

The reason would be that floating point types are not accurate, and
store an approximation of the value. You'll find that you will
frequently notice two variations of this, either slightly lower
(.99999999) or slightly higher (.0000000001).

Try using Decimal, or just format the value for output to round to a
specific number of digits.

--
Lasse Vågsæther Karlsen
mailto:la***@vkarlsen.no
http://presentationmode.blogspot.com/
PGP KeyID: 0xBCDEA2E3

[Hans Kesting]

sc*****@gmail.com explained on 20-6-2008 :

Hello,

i have the following problem in our project:
If I try to parse a string value with the following line
double x = double.Parse("39.95238", CultureInfo.InvariantCulture);
x contains 39.9523799999.... instead of the correct one.
What could be the reason for that?

Thanks in advance

Chris

See http://www.yoda.arachsys.com/csharp/floatingpoint.html

Hans Kesting

[Marc Gravell]

Double cannto guarantee to exactly represent every value, due to the
nature of floating-point arithmetic.

It sounds like you actually want a decimal; try:

decimal x = decimal.Parse("39.95238", CultureInfo.InvariantCulture);

Marc

[Duggi]

On Jun 20, 2:31 pm, [e-mail] wrote:

Hello,

i have the following problem in our project:
If I try to parse a string value with the following line
double x = double.Parse("39.95238", CultureInfo.InvariantCulture);
x contains 39.9523799999.... instead of the correct one.
What could be the reason for that?

Thanks in advance

Chris

http://www.yoda.arachsys.com/csharp/floatingpoint.html has good
information....

however, I did not face any such error using VS2008

-Cnu

[Ben Voigt [C++ MVP]]

sc*****@gmail.com wrote:

Hello,

i have the following problem in our project:
If I try to parse a string value with the following line
double x = double.Parse("39.95238", CultureInfo.InvariantCulture);
x contains 39.9523799999.... instead of the correct one.

Looks right to me... 7.9 repeating is equal to 8. Even if not repeating,
the total error is what, less than one trillionth of a percent?

What could be the reason for that?

Thanks in advance

Chris