"Jeff Dillon" <jef***@nowhere.com> wrote in message
news:%23ZVyVtj7GHA.2380@TK2MSFTNGP02.phx.gbl...
> How might I convert a string like 10.A (in hex) to it's decimal
> equivalent? Basically I have an input string like ((1F.A + 3A.D) - 1F.E)
> and need to calculate the result. Using Reflection and dynamic
> compilation, I was able to create a VB.NET equivalent of the older Eval
> function, but it only works with decimal numbers.
>
> Any thoughts? I know the logic to convert, but I was hoping for some
> built-in .NET methods that I could leverage
>
> jeff
>

news:1160706582.659986.232660@i3g2000cwc.googlegroups.com...
>I must admit, *fractional* hex is pretty weird; I've never seen it used
> and can't imagine what it would be used for.  But Stephany, I don't see
> why you think this is so ambiguous.
>
> It's pretty obvious to me that the data type is a hex Float.  What
> *unit* it represents - days, dollars, ducks - is irrelevant.
>
> In decimal, the numbers proceeding leftwards from the decimal point
> represent:
>  1's
>  10's
>  100's
>  1000's
>  etc.
>
> And from the right mean:
>  1/10's
>  1/100's
>  1/1000's
>  etc.
>
> Yes, that's all obvious - but stick with me.  In hex, proceeding from
> the left of the decimal point:
>  1's
>  16's
>  256's
>  4096's
>
> So we logically extend this consistent pattern to determine what the
> hex numbers to the right of the decimal represent:
>  1/16's
>  1/256's
>  1/4096's
>
> There's nothing magic about the minus sign either.  If present, it
> would denote a negative number regardless of numerical base.
>
> And we can do that for any number system and/or precision.  2.5
> (decimal) could be exactly represented as:
>
>  10.1 (binary)
>  2.4 (octal)
>  2.8 (hexadecimal)
>  2.G (base-36)
>
> Yes, I've actually used base-36; it uses the numbers and *all* the
> letters.  (I used it for shrinking a long decimal number, such as a
> drive serial, into the smallest possible easily human-readable/typable
> string for keycode-based software registration.)  I have some functions
> that will correctly convert decimal to/from *any* arbitrary numerical
> base, from binary to base-36, and everything inbetween.
>
> It doesn't do fractions, though!  And I'm sorry, but I can't help with
> the original query within the conditions specified - using a built-in
> VB language trick to facilitate conversion.
>

"Stephany Young" <noone@localhost> wrote in message
news:%23samZYl7GHA.4064@TK2MSFTNGP03.phx.gbl...
> The question has to asked:
>
>  Where does this 'input string' come from?
>
> If it comes from some abstract exercise on your part then your time would
> be better utilised musing in the question of 'Life, The Universe and
> Everything'.
>
> If it comes from some 'real world' data provider/producer, then you need
> to asking the question of that data provider/producer because they, and
> only they, can tell you what rules need to be applied and how they should
> be applied. If they can't, or won't tell you, then you are, (excuse my
> french), farting against thunder.
>
> That said, I must add -
>
> The decimal system has a widely acccepted set of rules that allow one to
> 'do math' on decimal numbers, regardless of whether the operands are
> integral or fractional. However, the decimal representation of a value
> must always be considered in it's context. For example, the number 10.5
> could represent 10 dollars and 50 cents or it could represent 10 and a
> half days or it could represent 10 and a half widgets. There are accepted
> extensions to decimal notation to indicate context like money being shown
> in conjunction with a currency symbol and there are other extensions to
> indicate signage (+ and -) while there are still other extensions to make
> the representation more readable, like thousands seperators. This makes it
> easy to show a number like $10,000.00 and everybody should interpret as
> ten thousand dollars without any ambiguity.
>
> Hexadecimal, on the other hand, is nothing more than a notational system
> and it primary use is for representing binary values in a more human
> readable form. It has no widely accepted extensions for indicating
> context, signage or readability.
>
> Take the hexadecimal value FF. What does it represent? It could represent
> 255 as a byte. It could represent -1 as a signed byte. It could represent
> 2 seperate 4-bit values of 15 each. The longer the string of hexadecimal
> characters the more permuatations there are of possible meanings.
>
> The next point is that hexadicamal notation has no concept of a
> 'hexadecimal point' and therefore has no rules regarding placeholding to
> the right of such a point (if it were to exist).
>
> You cannot apply the rules that govern the use of a decimal point because
> those rules relate only  to the the decimal system and have no meaning in
> any other 'base' system.
>
>
>
> "Jeff Dillon" <jef***@nowhere.com> wrote in message
> news:%23ZVyVtj7GHA.2380@TK2MSFTNGP02.phx.gbl...
>> How might I convert a string like 10.A (in hex) to it's decimal
>> equivalent? Basically I have an input string like ((1F.A + 3A.D) - 1F.E)
>> and need to calculate the result. Using Reflection and dynamic
>> compilation, I was able to create a VB.NET equivalent of the older Eval
>> function, but it only works with decimal numbers.
>>
>> Any thoughts? I know the logic to convert, but I was hoping for some
>> built-in .NET methods that I could leverage
>>
>> jeff
>>
>
>