On double parsing in C#

Question

I have the following code:

var d = double.Parse("4796.400000000001");
Console.WriteLine(d.ToString("G17", CultureInfo.InvariantCulture));

If I compile and run this using an x86 configuration in Visual Studio, then I get the following output:

4796.4000000000005

If I instead compile as x64 I get this:

4796.4000000000015

I realize that using 32 och 64 bit compilation must affect how double values are handled by the system, but given that C# defines double as being 64 bit, shouldn't the result of this operation be the same independently of what compilation configuration I use?

Additional observation

Based on a comment regarding double.Parse I wrote this code:

var d0 = double.Parse("4796.400000000001");
double d1 = 4796.400000000001;
Console.WriteLine("d0: " + d0.ToString("G17", CultureInfo.InvariantCulture));
Console.WriteLine("d1: " + d1.ToString("G17", CultureInfo.InvariantCulture));

I get the following output when compiling as x86:

d0: 4796.4000000000005
d1: 4796.4000000000005

But I get this when I compile as x64:

d0: 4796.4000000000015
d1: 4796.4000000000005

Notice how the values differ in the x64 version, but not in the x86 version.

Answer 1

I think the simple answer to this one is that this is a bug in .NET Framework. I filed the following ticket on the issue:

https://developercommunity.visualstudio.com/content/problem/488302/issue-with-double-parser.html

The issue has been closed as "won't fix" with the following motivation:

The change taken in .NET Core to enable stability in these calculations was large and carried more risk that we typically take in .NET Framework.