Is there any IsDouble() function in VB6? If I'm not mistaken, Double data type in VB6 is equivalent to float in SQL Server 2000. Your advice would be much appreciated.
A:
There's an IsNumeric() function that should work well enough. If that is inadequate for your needs can you also explain in what ways?
Joel Coehoorn
2009-04-08 16:20:56
Let me reveal the background, I need to check a string value which comes from a text file in order to insert into a field (SQL float datatype) of a database table (SQL Server 2000).
Kthurein
2009-04-08 16:37:54
Okay. The only problem with IsNumeric then is that it would allow an overflow: a number that is too big to fit in a float type.
Joel Coehoorn
2009-04-08 16:54:45
That's not correct, it will only accept values that fit into a Double. (IEEE standard 8 byte floating point number)
MarkJ
2009-04-08 17:23:43
MarkJ ... Do you mean that whichever value that satisfies IsNumeric() will not always overflow SQL 2K float data type? Am I right to say that?
Kthurein
2009-04-08 18:00:50
I think so - I'm not that familiar with SQL server. "VB6 Double variables are stored as IEEE 64-bit (8-byte) floating-point numbers ranging in value from -1.79769313486232E308 to -4.94065645841247E-324 for negative values and from 4.94065645841247E-324 to 1.79769313486232E308 for positive values"
MarkJ
2009-04-08 19:50:30
+1
A:
Function IsDouble(ByVal varValue As Variant) As Boolean
Dim dblTest As Double
On Error Resume Next
dblTest = CDbl(varValue)
IsDouble = Err.Number = 0
End Function
Will Rickards
2009-04-08 16:30:07
Thanks for your codes. Let me reveal the background, I need to check a string value which comes from a text file in order to insert into a field (SQL float datatype) of a database table (SQL Server 2000).
Kthurein
2009-04-08 16:39:15
Be careful what CDbl will accept as input though. I think it accepts trailing nonsense characters.
Will Rickards
2009-04-08 16:48:21
Nevermind, I was thinking of the Val function. But if you have international users you might want to test this against those too. I think CDBl uses the regional settings to do the conversion.
Will Rickards
2009-04-08 16:51:04
You can put parenthesis around it or call the CBool function if you really want to. But the above works.
Will Rickards
2009-04-08 17:25:59
Hmm... I know I have old code where I wanted to build a bool that way and wasn't able to. So I dug back (waaay back!) and found an example, and it turns out the reason was 'company policy' at my then work place. Old habits die hard, I guess.
Joel Coehoorn
2009-04-08 18:10:27
+1
A:
IsNumeric() is fine, it will only accept values that fit into Doubles. It is regionally aware, i.e. for French regional settings the decimal separator is a comma.
I just tried this in the Immediate window.
Debug.Print IsNumeric("4e308")
False
The definition of a VB6 Double in the manual is "VB6 Double variables are stored as IEEE 64-bit (8-byte) floating-point numbers ranging in value from -1.79769313486232E308 to -4.94065645841247E-324 for negative values and from 4.94065645841247E-324 to 1.79769313486232E308 for positive values".
I think that's the same as a SQL Server float, going by the online docs. "Floating precision number data with the following valid values: -1.79E + 308 through -2.23E - 308, 0 and 2.23E + 308 through 1.79E + 308."
MarkJ
2009-04-08 17:23:06
+3
A:
Actually your much better off using the Vartype function.
Private Function IsDouble(ByVal value As Variant) As Boolean
IsDouble = (VarType(value) = vbDouble)
End Function
Kind Regards Noel
Bigtoe
2009-04-17 07:20:33