Double.MaxValue Casting Problems

#1

I have some code that takes Double.MaxValue and converts it to a string, but
when I try to convert it back to a double, it fails. Shouldn't the value be
able to be converted back to a double without error?

Here is a simple code sample that demonstrates the problem:

try
{
Double dbl = double.MinValue;
//String sdbl = dbl.ToString(); // This errors as well
String str = dbl.ToString("N");

// This throws "Value was either too large or too small
for a Double."
Double dbl2 = Convert.ToDouble(str);
}
catch (Exception ex)
{
System.Diagnostics.Debug.Write(ex.Message);
}

#2

Floating point operations are always approximative, conversions of them to
string even worse.
If you need to convert, it might be better to check the inherent limits
(Min/Max/Infinity etc) and handle them as special case, like:

Double dbl2;

if(str!=double.MinValue.ToString())
dbl2 = Convert.ToDouble(str);
else
dbl2=double.MinValue

"Kevin Blakeley" <KevinBlakeley (AT) discussions (DOT) microsoft.com> ha scritto nel
messaggio news:13280E1B-CDAC-4939-B829-B9FA2CADB7D8 (AT) microsoft (DOT) com...

Quote:

I have some code that takes Double.MaxValue and converts it to a string,
but
when I try to convert it back to a double, it fails. Shouldn't the value
be
able to be converted back to a double without error?

Here is a simple code sample that demonstrates the problem:

try
{
Double dbl = double.MinValue;
//String sdbl = dbl.ToString(); // This errors as well
String str = dbl.ToString("N");

// This throws "Value was either too large or too small
for a Double."
Double dbl2 = Convert.ToDouble(str);
}
catch (Exception ex)
{
System.Diagnostics.Debug.Write(ex.Message);
}

#3

Kevin Blakeley wrote:

Quote:

I have some code that takes Double.MaxValue and converts it to a string, but
when I try to convert it back to a double, it fails. Shouldn't the value be
able to be converted back to a double without error?

Here is a simple code sample that demonstrates the problem:

try
{
Double dbl = double.MinValue;
//String sdbl = dbl.ToString(); // This errors as well
String str = dbl.ToString("N");

// This throws "Value was either too large or too small
for a Double."
Double dbl2 = Convert.ToDouble(str);
}
catch (Exception ex)
{
System.Diagnostics.Debug.Write(ex.Message);
}
Perhaps you should try the round-trip format string instead

String str = dbl.ToString("R");

Peter

#4

Thanks! That worked like a champ. I tried a few of the fomatting types but
did not try that one. I even tested to see if my value was equal to
Double.Minvalue and it evaluated to true.

Thanks again.

"Peter Bromley" wrote:

Quote:

Kevin Blakeley wrote:
I have some code that takes Double.MaxValue and converts it to a string, but
when I try to convert it back to a double, it fails. Shouldn't the value be
able to be converted back to a double without error?

Here is a simple code sample that demonstrates the problem:

try
{
Double dbl = double.MinValue;
//String sdbl = dbl.ToString(); // This errors as well
String str = dbl.ToString("N");

// This throws "Value was either too large or too small
for a Double."
Double dbl2 = Convert.ToDouble(str);
}
catch (Exception ex)
{
System.Diagnostics.Debug.Write(ex.Message);
}
Perhaps you should try the round-trip format string instead

String str = dbl.ToString("R");

Peter

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Double.MaxValue Casting Problems

Dotnet Framework microsoft.public.dotnet.framework

Double.MaxValue Casting Problems - 02-15-2007 , 11:26 AM

Re: Double.MaxValue Casting Problems - 02-15-2007 , 11:58 AM

Re: Double.MaxValue Casting Problems - 02-15-2007 , 04:53 PM

Re: Double.MaxValue Casting Problems - 02-15-2007 , 05:01 PM