Convert Hexadecimal to Floating Point

Call me an idiot, but for the life in me i cannot figure out how to do a simple conversion......
I need to convert
FB7E0E41 to 8.9060
32 bit IEEE Hex to decimal
can ANYONE Help ME!!!!!

Thanks
Nick Stone

You're not an idiot and and it's not a simple conversion. As far as I know there is no available ieee hex to float functions for vb.

Here's how you break down the hex value.
You're going to have to do a search for more info
because this might get confusing.

FB7E0E41 (hex)
1111 1011 0111 1110 0000 1110 0100 0001 (binary)

Reading the bits left to right....

The Sign of the mantissa (and therefore the number) is 1 (MSB) which represents a negative value.

The Exponent is 11110110 (binary) or 246 decimal.
The exponent field is represented in excess 127 so the exponent value is 119

The Mantissa is 11111100000111001000001 binary
with the implied leading 1, the mantissa is (1).FC1C82 (hex)

to get the floating point representation....

1*2^0 /* 1 */
+ 1*2^-1 + 1*2^-2 + 1*2^-3 + 1*2^-4 /* F */
+ 1*2^-5 + 1*2^-6 + 0*2^-7 + 0*2^-8 /* C */
+ 0*2^-9 + 0*2^-10 + 0*2^-11 + 1*2^-12 /* 1 */
+ 1*2^-13 + 1*2-14 + 0*2^-15 + 0*2^-16 /* C */

etcetera...

The floating point representation is therefore -1.98480999 times 2 to the 119

Decimal equivalent: -1.31913E+036

I don't know where you got the 8.906 value.

Curt

I'm not familiar with the IEEE thing or the exact specification of floating point, but here are two functions to convert any number from decimal to any base and back again. Using these i was able to convert the original number in base 16 to base 10 and then to the binary number that Curt came up with. So, I think these might help:

public Function ConvertDecToBaseN(byval dValue as Double, optional byval byBase as Byte = 16) as string
Const BASENUMBERS as string = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
Dim sResult as string
Dim dRemainder as Double

on error GoTo ErrorHandler

sResult = ""

If (byBase < 2) Or (byBase > 36) then GoTo Done

dValue = Abs(dValue)

Do
dRemainder = dValue - (byBase * Int((dValue / byBase)))
sResult = mid$(BASENUMBERS, dRemainder + 1, 1) & sResult
dValue = Int(dValue / byBase)

Loop While (dValue > 0)

Done:
ConvertDecToBaseN = sResult
Exit Function

ErrorHandler:
Err.Raise Err.Number, "ConvertDecToBaseN", Err.Description
End Function

public Function ConvertBaseNToDec(byval dValue as string, optional byval byBase as Byte = 16) as string
Const BASENUMBERS as string = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
Dim sResult as string
Dim lReturn as Double
Dim n as Integer

on error GoTo Handler

If (byBase < 2) Or (byBase > 36) then Exit Function

n = 0

Do
lReturn = ((InStr(1, BASENUMBERS, mid(dValue, (len(dValue) - n), 1)) - 1) * (byBase ^ n)) + lReturn
n = n + 1
Loop Until n = len(dValue)

ConvertBaseNToDec = CStr(lReturn)

Exit Function

Handler:
Err.Raise Err.Number, "ConvertBaseNToDec", Err.Description
End Function




You could probably modify these to go directly from any base to any other base, but I haven't had time to do that yet.

Also, these dont seem to handle rational or irrational numbers (non-whole numbers), sorry.

hope this helps,

John

John Pirkey
MCSD
http://www.ShallowWaterSystems.com
http://www.stlvbug.org

These two things just dont seem to work

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