Currency Converter

The code for the currency converter on Valhalla's Tools page.

<?php
/*
* Author: ynori7
* Copyright: halls-of-valhalla.org
*/

//rates from X to USD
$rates = array();
$rates['Argentine Peso'] = 4.42411;
$rates['Australian Dollar'] = 0.947301;
$rates['Botswana Pula'] = 6.78887;
$rates['Brazilian Real'] = 1.64615;
$rates['British Pound'] = 0.622101;
$rates['Brunei dollar'] = 1.2086;
$rates['Bulgarian Lev'] = 1.38719;
$rates['Canadian Dollar'] = 0.992411;
$rates['Chilean Peso'] = 463.951;
$rates['Chinese Yuan'] = 6.39052;
$rates['Colombian Peso'] = 1792.04;
$rates['Croatian Kuna'] = 5.31031;
$rates['Danish Krone'] = 5.2835;
$rates['Euro'] = 0.70927;
$rates['Hong Kong Dollar'] = 7.79382;
$rates['Hungarian Forint'] = 196.631;
$rates['Iceland Krona'] = 116.233;
$rates['Indian Rupee'] = 45.9848;
$rates['Indonesian Rupiah'] = 8559.17;
$rates['Iranian Rial'] = 10616;
$rates['Israeli New Shekel'] = 3.66934;
$rates['Japanese Yen'] = 77.3743;
$rates['Kazakhstani Tenge'] = 146.8;
$rates['Kuwaiti Dinar'] = 0.2733;
$rates['Latvian Lat'] = 0.503085;
$rates['Libyan Dinar'] = 1.9324;
$rates['Lithuanian Litas'] = 2.44897;
$rates['Malaysian Ringgit'] = 2.98298;
$rates['Mauritius Rupee'] = 28.1745;
$rates['Mexican Peso'] = 12.537;
$rates['Nepalese Rupee'] = 73.45;
$rates['New Zealand Dollar'] = 1.20377;
$rates['Norwegian Kroner'] = 5.38797;
$rates['Omani Rial'] = 0.3845;
$rates['Pakistan Rupee'] = 87.4669;
$rates['Philippine Peso'] = 42.3179;
$rates['Qatari Rial'] = 3.64;
$rates['Romanian Leu'] = 3.01724;
$rates['Russian Ruble'] = 29.5807;
$rates['Saudi Riyal'] = 3.75;
$rates['Singapore Dollar'] = 1.20838;
$rates['South African Rand'] = 7.13398;
$rates['South Korean Won'] = 1074.46;
$rates['Sri Lanka Rupee'] = 109.964;
$rates['Swedish Krona'] = 6.44641;
$rates['Swiss Franc'] = 0.853678;
$rates['Taiwan Dollar'] = 29.1043;
$rates['Thai Baht'] = 29.9149;
$rates['Trinidad/Tobago Dollar'] = 6.38943;
$rates['Turkish Lira'] = 1.76998;
$rates['US Dollar'] = 1; //this is the default because i had to pick something
$rates['Venezuelan Bolivar'] = 4.29376;

if(isset($_POST['amount']) and isset($_POST['currency1']) and isset($_POST['currency2']))
{
  $amount = number_format((double) $_POST['amount'], 2);
  $c1 = $_POST['currency1'];
  $c2 = $_POST['currency2'];
  if($amount<=0 or !isset($rates[$c1]) or !isset($rates[$c2]))
  {
    echo "<p>Invalid input.</p><br/>\n";
  }
  else{
    $result = number_format($amount/$rates[$c1], 2); //to dollars
    $result = number_format($result*$rates[$c2], 2); //to new currency
    echo "Result = $result $c2(s).";
  }

}

echo "<p>Note: Exchange rates last updated September 6th, 2011.</p>
<form action='' method='POST'>
<table>
<tr>
  <td>Amount To Convert:</td>
  <td><input type='text' name='amount' maxlength='50'></td>
</tr>
<tr>
  <td><u>From:</u></td>
  <td style='padding-left:50px'><u>To:</u></td>
</tr>
<tr>
  <td>";
foreach(array_keys($rates) as $currency)
  echo "<input type='radio' name='currency1' value='$currency'>$currency<br/>\n";
echo "</td>
  <td style='padding-left:50px'>";
foreach(array_keys($rates) as $currency)
  echo "<input type='radio' name='currency2' value='$currency'>$currency<br/>\n";
echo "</td>
</tr>
<tr>
  <td colspan='4'><center><input type='submit' value='submit'></center></td>
</tr>
</table>
</form>\n";
?>