base36 conversions

mrbaseball34

I have a need for some Integer to base36 conversions.

I have the code in Delphi but need a PHP version now.

Here is the Delphi code:

const XX = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ' ;
Function Base36ToInt (const S: string): Int64;
var i: integer;
begin
  Result := 0;
  For i := 1 to length(S) do 
    Result := Result * 36 + Pred(Pos(UpCase(S[i]), XX)) ;
end;

Function IntegerToBase36 (I: Int64): string;
begin
  Result := '';
  Repeat
    Result := XX[Succ(I mod 36)] + Result ;
    I := I div 36;
  Until I=0;
end;

Here is my first shot at it but it isn't working.

function str_split($str, $len=1)
{
  if ($len < 1) return false;
  $tmp_str = array();
  for ($offset = 0; $offset < strlen($str); $offset += $len)
  {
   $tmp_str[] = substr($str, $offset, $len);
  }
  return $tmp_str;
}

function base36toint($s){

  $xx = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ';
  $x = 0;
  $str = str_split($s);
  for ($i = 1; strlen($s); $i++) {
    $a = strpos($xx, $str[$i]);
    $x = $x * (36 + $a);
  }
  return $x;
}

Can anyone help out?

Mordecai

What's wrong with [man]base_convert/man?

tsinka

Hi,

the following code should do that:

<?PHP
  $xx = "0123456789abcdefghijklmnopqrstuvwxyz";

  $base36 = "10Z";
  $base36 = strtolower($base36);

  $intval = 0;
  $len = strlen($base36);

  for ($i=0;$i<$len;$i++) {
    $intval += pow(36,$len-1-$i) * strpos($xx,$base36[$i]);
  }

  echo $intval;
?>

Thomas

mrbaseball34

Originally posted by Mordecai
What's wrong with [man]base_convert/man?

Didn't know it existed; works perfectly. Thanks a lot!!
😃

Mordecai

PHP has a lot of functions that you'd kick yourself over. Most of them are even named after what they do. 🙂

Also, since your question is resolved, please click the Mark Thread Resolved link.

mrbaseball34

After taking another look at it with a test script, this code returns an entirely different result than the Delphi code posted above.

function base36toint($s){
  $x = base_convert($s, 36, 10);
  return $x;
} 

function inttobase36($s) {
  $x = base_convert($s, 10, 36);
  return $x;
}

I test with the number : 5555444433331111

and am expecting a result of :
177XYGYLBFLZ4

but 1ip8nxua3s7 is returned:

Another developer gets cesv7b0f53
returned using the EXACT same code.

So why the differences?

tsinka:
Your code doesn't return the correct result either when trying to convert the Base36 value of 177XYGYLBFLZ4.

It returns 5.68877509973E+018.