Permite convertir numero de una base a otra

PLAIN TEXT
PHP:
  1. <?
  2. /****************************************
  3.   convertBase($number, $originalBase, $destinationBase);
  4.  
  5.   Author: Chris Heald
  6.   Creation date: 1/16/02
  8.   Purpose:
  9.   Use to convert a number in any base from 2 to
  10.   36 to any other base from 2 to 36.
  11.   ie: convertBase("FF",16,10) returns 255. You can
  12.   also use HEX, BINARY, BASE10, DECIMAL
  13.   and OCT in place of numeric
  14.   values for the bases. ie:
  15.   convertBase("FF",HEX,BINARY) returns 11111111.
  16.  
  17.   HEX    : 16
  18.   BASE10 : 10
  19.   DECIMAL: 10
  20.   OCT    :  8
  21.   BINARY :  2
  22.  
  23.   Possible future enhancements:
  24.     Even more bases supported. We could use lower case
  25.     and upper case letters as seperate digits, but that could get
  26.     confusing. The benefit of this would be a maximum range of 62 bases.
  27.    
  28.   This was an exericse I did in my free time. Please feel free
  29.   to expand or enhance it, and feel free to email me if you have questions.
  30.  
  32. ****************************************/
  33.  
  34. define("HEX",16);
  35. define("BINARY",2);
  36. define("OCT",8);
  37. define("BASE10",10);
  38. define("DECIMAL", 10);
  39. function convertBase($number, $fromBase = 10, $toBase = 2) {
  40.  
  41.   if($toBase> 36 || $toBase <2)   
  42.   //check base validity
  43.     return "Invalid originating base.";
  44.   if($fromBase> 36 || $fromBase <2)
  45.     return "Invalid destination base.";
  46.    
  47.   @list($number, $decimal) = explode(".",$number);
  48.   for($i = 0; $i <strlen($number); $i++) {   
  49.   //convert to base 10
  50.     $digit = substr($number, $i, 1);
  51.     if(eregi("[a-z]",$digit)) {
  52.       $x = ord($digit) - 65 + 10;
  53.       if($x> $fromBase)
  54.         $x -= 32;
  55.       $digit = $x;
  56.     }
  57.     @$base10 += $digit * (pow($fromBase, strlen($number) - $i - 1));
  58.   }
  59.   $number = $base10;
  60.   if($toBase == 10)
  61.     return $number;
  62.   $q = $number;
  63.   while($q != 0) {   
  64.   //convert base 10 equivalent to specified base
  65.     $r = $q % $toBase;
  66.     $q = floor($q / $toBase);
  67.     if($r> 9)
  68.       $r = chr(($r - 9) + 64);
  69.     @$baseres = "$r" . "$baseres";
  70.   }
  71.   return $baseres;
  72. }
  73.  
  74. ?>

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