Re: converting arbitrary long decimals to hex?

[KHMan <keinhong@...>]

Norbert Kiesel wrote:
> I'm trying to convert arbitrary long decimals (encoded as a string of
> digits) to it's hex representation (i.e. a string of hexadecimal
> digits).  For short decimals, format('%x') is the way to go.  That
> looses out however for e.g. '5766297887677882160' because we loose
> precision when it's internally converted to a (floating point) number:
> it returns '50060160b0202000' instead of '50060160b0201f30'.
>
> So please help me out.  Here is what I came up with, is that correct or
> is there a better/faster way to do it (I know that BigNum can do it, but
> this is not pure Lua).

At first glance, I don't believe calculating partial results from 
left to right in this way works... have you actually tried the code?

> function tohex(decimal)
> [snip]
>       for i = 1, #decimal do
> [snip]

Tons of FLOSS arbitrary precision code around, I think they are 
worth a look.

--
Cheers,
Kein-Hong Man (esq.)
Kuala Lumpur, Malaysia