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Output all digits of a double in VBA macro

Question asked by Jana Stahn on Feb 15, 2017
Latest reply on Jul 27, 2020 by Michael Foegelle

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I am trying to check values of dimensions with a VBA macro.

I already have a Dimension object (let's call it "d") and I can output the value via

Debug.Print d.Value

but this only outputs the first 15 digits. How can I output all 17 digits?

MSDN says (here Double.ToString Method (String) (System) ) that there exists a method to do this:

Double.ToString("G17")

But if I write in the macro the following lines

...

Dim val As Double

val = d.Value

Dim str as String

str = val.ToString("G17")

...

then I get an error that the method (ToString) is not known.

I am using SolidWorks2016.

Keith Rice Feb 15, 2017 10:46 AM

Correct Answer

The MSDN article you linked to is for .NET, not VBA. (Note where it says ".NET Framework" under the main heading.) You would need to recreate the macro as a .NET program in order to use that method. That method does not exist in VBA, hence it is not known.

Honestly, I am curious why you are wanting to test a dimension out to that many digits since there is no realistic way to even machine something with that amount of precision, assuming we are talking about normal units of measure.

Keith

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Keith Rice Feb 15, 2017 10:46 AM

Keith

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Michael Foegelle @ Keith Rice on Jul 23, 2020 6:39 PM

Hi Keith:

I can give you a good reason. Debugging bugs in SolidWorks. I have a macro that runs calculations to build surfaces and have found a repeatable way to crash SW 2020 hard (restart due to a thread causing an access violation). I have traced my code down to the exact point that causes the crash and want to make a test example with just the two triangles that cause the crash when combined into a single surface. If I use the debug print output of those values, no crash. If I save them to a binary file and reload them into a simplified chunk of code, then it crashes. It's those last few digits that SW may not need that are actually enough to make it crash. I want to be able to just assign those numbers in code rather than having to read them from a file so I can just paste that into the crash report. Can't do it without a way to get the full number of digits and assign them back to a double. A Union would work, but that doesn't exist in VBA either.

Michael

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Solid Air @ Michael Foegelle on Jul 23, 2020 6:52 PM

I suppose multipling by 100 would not work? The number is actually stored as meters in SW so you might look at that too.

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Michael Foegelle @ Solid Air on Jul 24, 2020 9:02 AM

10 or 100 are not exact binary values, so no, that wouldn't help. The numerical error of the floating point value would change as you multiplied. I debated writing something to multiply by two and build up a variable that way, but by that time I'd probably just as well find an alternate solution. What I did that appears to work (at least I can replicate the crash using the result) is the following:

Function DoubleToExactString(d As Double) As String
   Dim s As String
   s = d
   DoubleToExactString = s & "+" & (d - CDbl(s))
End Function

Then I can drop the text string back into code and the number produced by adding the two values does appear to match the original, at least on the variables I've tested by checking the difference again.

Michael

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Artem Taturevych @ Michael Foegelle on Jul 24, 2020 12:05 AM

Assign them to string variable and use CDbl to convert to double

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Michael Foegelle @ Artem Taturevych on Jul 24, 2020 9:04 AM

Thanks Artem:

I think you're looking in the wrong direction (literally). =) The question is how to get a string that accurately represents a Double, not how to get a double from a string. It would appear that the string conversion, even with formatting, was written for Floats and there's no way to get it to print enough digits to match the number of digits in a Double.

Michael

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Artem Taturevych @ Michael Foegelle on Jul 25, 2020 5:08 AM

Hi Michael,

Got you. Sorry I was confused when you said ‘when I save them to binary files’ as I thought you mean doubles but I think you mean the temp bodies stored in the file via IBody2::Save

Thanks,

Artem

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Michael Foegelle @ Artem Taturevych on Jul 27, 2020 9:42 AM

Hi Artem:

Sorry for the confusion. The reference to a binary file was about the doubles. I made the point in my code that was causing the crash write all its variables to a binary file (as opposed to text output) so that I could read that in to a stub of code and replicate the crash. However, what I wanted was to actually put those variables in the code stub directly, which meant I needed an accurate text representation of the binary content. My trick of adding two values, the initial text output and a remainder, appears to work fine. Now for Dassault to just fix the bug!

Beo

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8 Replies

Keith Rice Feb 15, 2017 10:46 AM
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Correct Answer
The MSDN article you linked to is for .NET, not VBA. (Note where it says ".NET Framework" under the main heading.) You would need to recreate the macro as a .NET program in order to use that method. That method does not exist in VBA, hence it is not known.

Honestly, I am curious why you are wanting to test a dimension out to that many digits since there is no realistic way to even machine something with that amount of precision, assuming we are talking about normal units of measure.

Keith
SolidWorks API Training and Services
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- Michael Foegelle @ Keith Rice on Jul 23, 2020 6:39 PM
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  Correct Answer
  Hi Keith:
  
  I can give you a good reason. Debugging bugs in SolidWorks. I have a macro that runs calculations to build surfaces and have found a repeatable way to crash SW 2020 hard (restart due to a thread causing an access violation). I have traced my code down to the exact point that causes the crash and want to make a test example with just the two triangles that cause the crash when combined into a single surface. If I use the debug print output of those values, no crash. If I save them to a binary file and reload them into a simplified chunk of code, then it crashes. It's those last few digits that SW may not need that are actually enough to make it crash. I want to be able to just assign those numbers in code rather than having to read them from a file so I can just paste that into the crash report. Can't do it without a way to get the full number of digits and assign them back to a double. A Union would work, but that doesn't exist in VBA either.
  
  Michael
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  - Solid Air @ Michael Foegelle on Jul 23, 2020 6:52 PM
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    I suppose multipling by 100 would not work? The number is actually stored as meters in SW so you might look at that too.
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    - Michael Foegelle @ Solid Air on Jul 24, 2020 9:02 AM
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      10 or 100 are not exact binary values, so no, that wouldn't help. The numerical error of the floating point value would change as you multiplied. I debated writing something to multiply by two and build up a variable that way, but by that time I'd probably just as well find an alternate solution. What I did that appears to work (at least I can replicate the crash using the result) is the following:
      
      Function DoubleToExactString(d As Double) As String
         Dim s As String
         s = d
         DoubleToExactString = s & "+" & (d - CDbl(s))
      End Function
      
      Then I can drop the text string back into code and the number produced by adding the two values does appear to match the original, at least on the variables I've tested by checking the difference again.
      
      Michael
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  - Artem Taturevych @ Michael Foegelle on Jul 24, 2020 12:05 AM
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    Assign them to string variable and use CDbl to convert to double
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    - Michael Foegelle @ Artem Taturevych on Jul 24, 2020 9:04 AM
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      Thanks Artem:
      
      I think you're looking in the wrong direction (literally). =) The question is how to get a string that accurately represents a Double, not how to get a double from a string. It would appear that the string conversion, even with formatting, was written for Floats and there's no way to get it to print enough digits to match the number of digits in a Double.
      
      Michael
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      - Artem Taturevych @ Michael Foegelle on Jul 25, 2020 5:08 AM
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        Hi Michael,
        
        Got you. Sorry I was confused when you said ‘when I save them to binary files’ as I thought you mean doubles but I think you mean the temp bodies stored in the file via IBody2::Save
        
        Thanks,
        Artem
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        Michael Foegelle @ Artem Taturevych on Jul 27, 2020 9:42 AM
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        Hi Artem:
        
        Sorry for the confusion. The reference to a binary file was about the doubles. I made the point in my code that was causing the crash write all its variables to a binary file (as opposed to text output) so that I could read that in to a stub of code and replicate the crash. However, what I wanted was to actually put those variables in the code stub directly, which meant I needed an accurate text representation of the binary content. My trick of adding two values, the initial text output and a remainder, appears to work fine. Now for Dassault to just fix the bug!
        
        Beo
        Like • Show 1 Like1
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Output all digits of a double in VBA macro

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