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***drdebcol*** · (This post was last modified: 09-15-2009 12:21 AM by drdebcol.)

There are some programming tasks that have conversion between different number systems included. That's why i made any to dec and dec to any converter.
I have been doing a bit of research on this and i came to solution.
I made Dec to Bin converter which is pretty simple(http://www.pro9ramming.com/showthread.php?tid=82), but comparing to this "code".
Okay code tells the best about itself, and if you want to find more about converting, you can use wiki.
So code in TPW :

Code:

program number_systems;

uses wincrt;

var

number,option:string;

syst,nu:integer;

label top;

function inttostr(n:longint):string;

var

  i:integer;

  h:array[0..9] of string;

  b:boolean;

  s:string;

begin

h[0]:='0';

h[1]:='1';

h[2]:='2';

h[3]:='3';

h[4]:='4';

h[5]:='5';

h[6]:='6';

h[7]:='7';

h[8]:='8';

h[9]:='9';

b:=false;

s:='';

if n<0 then

begin

 n:=-n;

 b:=true;

end;

repeat

 begin

   s:=h[n mod 10]+s;

   n:=n div 10;

 end;

until n=0;

if b=true then

s:='-'+s;

inttostr:=s;

end;

function change_to_dec(numb:string; system:integer):longint;

var

  i,br:integer;

  s:longint;

function power(n,k:longint):longint;

var

  i,p:longint;

begin

  if k=0 then

  begin

  power:=1;

  end

  else

  begin

  p:=1;

  for i:=1 to k do

  p:=p*n;

  power:=p;

  end;

end;

function return_value(s:string):integer;

begin

  if s='0' then

  return_value:=0;

  if s='1' then

  return_value:=1;

  if s='2' then

  return_value:=2;

  if s='3' then

  return_value:=3;

  if s='4' then

  return_value:=4;

  if s='5' then

  return_value:=5;

  if s='6' then

  return_value:=6;

  if s='7' then

  return_value:=7;

  if s='8' then

  return_value:=8;

  if s='9' then

  return_value:=9;

  if s='A' then

  return_value:=10;

  if s='B' then

  return_value:=11;

  if s='C' then

  return_value:=12;

  if s='D' then

  return_value:=13;

  if s='E' then

  return_value:=14;

  if s='F' then

  return_value:=15;

end;

begin

s:=0;

br:=length(numb)-1;

  for i:=1 to length(numb) do

  begin

    s:=s+return_value(numb[i])*power(system,br);

    br:=br-1;

  end;

  change_to_dec:=s;

end;

function dec_to_any(dec:longint;system:integer):string;

var

  s:string;

  function return_value(k:integer):string;

  begin

   if k<10 then

   return_value:=inttostr(k)

   else

     begin

      if k=10 then

      return_value:='A';

      if k=11 then

      return_value:='B';

      if k=12 then

      return_value:='C';

      if k=13 then

      return_value:='D';

      if k=14 then

      return_value:='E';

      if k=15 then

      return_value:='F';

     end;

  end;

begin

  s:='';

  repeat

    begin

     s:=return_value(dec mod system)+s;

     dec:=dec div system;

    end;

  until dec=0;

  dec_to_any:=s;

end;

begin

 top:

 writeln('Number system converter 1.0');

 writeln('Options :');

 writeln('1 - Any to Decimal number system');

 writeln('2 - Decimal to any number system');

 repeat

   begin

    writeln('Enter option :');

    readln(option);

   end;

 until (option='1') or (option='2');

 if option='1' then

 begin

 writeln('Enter number :');

 readln(number);

 writeln('Enter system :');

 readln(syst);

 writeln('Decimal is :');

 writeln(change_to_dec(number,syst));

 end

 else

 begin

 writeln('Enter number :');

 readln(nu);

 writeln('Enter system :');

 readln(syst);

 writeln('Number is :');

 writeln(dec_to_any(nu,syst));

 end;

 writeln;

 writeln('Press Enter to try again !');

 readln;

 clrscr;

 goto top;

end.

G4143 · (This post was last modified: 09-03-2009 08:32 AM by G4143.)

Here's a question for you. Do you know why functions like

strtol()

only offer number conversions from base 2 to base 36...G4143

***drdebcol*** · 09-03-2009, 05:08 PM

I really don't know. Maybe base 36 has something to do with some calculus.
I was really thinking about this issue and i think theoretically that the smallest base of number systems is 2,
so that makes a question "What is the biggest base of number systems ?"
Well decimal system with
Base 10 has 10 digits (0123456789)
Base 11 has one letter (0123456789A)
Base 12 has two letters (0123456789AB)
*
*
*
and so on till end of English Alphabet
which is number of digits + number of letters and that is 36 because
10 digits (0123456789) and 26 letters (A,B,C . . . X,Y,Z)
10+26=36
Maybe that is the answer, i really couldn't find better !

G4143 · 09-03-2009, 11:42 PM

Yep, that's it. The limiting factor is the ten digits 0 - 9 plus the letters a - z....G4143

***drdebcol*** · 09-04-2009, 12:21 AM

(09-03-2009 11:42 PM)G4143 Wrote: Yep, that's it. The limiting factor is the ten digits 0 - 9 plus the letters a - z....G4143

Yeah, that was a fast logical conclusion