Source Code: | Run it! |

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<?php
$maxBase=36;
$dg=array(0=>"0", "1", "2", "3", "4", "5", "6", "7", "8", "9",
             "A", "B", "C", "D", "E", "F", "G", "H", "I", "J",
             "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T",
             "U", "V", "W", "X", "Y", "Z");
if(isset($_GET['number'])AND isset($_GET['base'])AND isset($_GET['newbase'])){
  $n1 = strval($_GET['number']);
  $b1 = intval($_GET['base']);
  $b2 = intval($_GET['newbase']);
  if(($b1>$maxBase)OR($b2>$maxBase)){
    echo '<font color="ff0000">'.
         'ERROR: Neither base can be larger than 36!'.
         '</font><hr/>';
  }else{
    $num=0;
    while(strlen($n1)>0){
      $num = $num * $b1;
      $num = $num+array_search($n1{0},$dg);
      $n1 = substr($n1, 1);
    }
    $n2="";
    while($num>0){
      $n2 = $dg[$num % $b2].$n2;
      $num = floor($num/$b2);
    }
    echo "The number ".$n1." (base ".$b1.") in base ".$b2." is ".$n2.".<hr/>";
  }
}
?>