Headaches with large base 11 numbers 1

[Nosferatu]

Hey...

Can anybody give me some clues on how to deal efficiently with extremely large numbers?
I have to convert these huge base11 numbers (64 digits) to base36 numbers and my mind is starting to self-destruct.

Does anybody have some ideas in this area?
First of all, I don't know how to convert such a number to binary (from a character string) efficiently.
I can imagine writing addition algorithms in base11, but I don't think that what I'd do would be efficient for such numbers.

Any help is appreciated...
Thank you. [red]Nosferatu[/red]
We are what we eat...
There's no such thing as free meal...
once stated: methane@personal.ro

 

[xwb]

Interesting concept. Presumably the base 11 is 0-A and base 36 is 0-Z. If you are using a MS compiler, have a look at strtol. Here is a sample program

#include <stdio.h>
#include <stdlib.h>

main ()
{
char* base11[] = {&quot;A&quot;, &quot;10&quot;, &quot;100&quot;, &quot;123A&quot; };
char* last;
long val11, val16, val36;
int ii;

for (ii = 0; ii < sizeof(base11)/sizeof(base11[0]); ii++)
{
val11 = strtol (base11[ii], &last, 11);
val16 = strtol (base11[ii], &last, 16);
val36 = strtol (base11[ii], &last, 36);
printf (&quot;%s base 11 is %d base 10\n&quot;, base11[ii], val11);
printf (&quot;%s base 16 is %d base 10\n&quot;, base11[ii], val16);
printf (&quot;%s base 36 is %d base 10\n&quot;, base11[ii], val36);
}

return 0;
}

 

[jamisar]

why not 'dc', no limits and works on char-strings,
try on you unix:
echo &quot;scale=99; (33/7)*(10^7)&quot;|/bin/bc
'bc' is a preprocessor to 'dc'
bc -c gives the 'dc' syntax.
i posted 'pipe to dc' in this forum -----------
when they don't ask you anymore, where they are come from, and they don't tell you anymore, where they go ... you'r getting older !

 

[Nosferatu]

Thanks Jamisar, I will try that, but I am working this on a NT/2000 platform. It would be interesting to see if there's a source code for the dc program.
But is the program working with extremely large numbers?
(xwb - the numbers to be processed are way above the ranges handled by any integer datatype on any computer I know - 64 digits!!!)
I tried to look at the gnu-gmp library but really freaked-out...

The solution I am aiming at is to make use of the fact that 36 = 6*6 so, if I will convert the number to base6, obtaining the radix 36 representation will be trivial - group 2 digits from base6 together to form 1 digit in base 36, the same idea that works for base2-base4,8,16...
[red]Nosferatu[/red]
We are what we eat...
There's no such thing as free meal...
once stated: methane@personal.ro

 

[chipperMDW]

You might want to search for some math libraries that have a &quot;HugeInt&quot; class or somesuch. I know people have written them, I've just never needed to use one so I don't know of any good ones. I'm sure there're also libraries out there to do the base conversion.

I'll check on those and let you know if I find anything.

 

[xwb]

I know this is a C forum but if you ever think of trying C++, you could look at

http://codeguru.earthweb.com/algorithms/Calc.html

 

[jamisar]

Nosferatu, i found an old (still running) dc-src file
if interested send an email to priam@freenet.de
-----------
when they don't ask you anymore, where they are come from, and they don't tell you anymore, where they go ... you'r getting older !