Question

I have to program a currency converter in php, which converts the following currencys:

EUR -> USD
EUR -> GBP

The code must have a good structure and clear. My code looks like this:

In index.php, I write the html inputs as follow:

                <select name="fT">
                    <option value="euro-usd@EUR-USD">EUR -> USD</option>
                    <option value="euro-gbp@EUR-GBP">EUR -> GBP</option>
                <select>
                   <input type="text" name="amount" id="amount" value="">
                   <input type="submit"/>

convert.php looks like this:

<?php
include ("functions.php");
$fT = $_POST['fT'];
$amount = $_POST['amount'];

$valueAndText = explode('@', $fromTo);
$fromTo = $valueAndText[0];
$text = explode('-', $valueAndText[1]);
$from = $text[0];
$to = $text[1];

echo convertCurr($fT, $amount) ;
?>

Any suggestion for improving this code?

Answer 1

You can place the share prices in a config file that you can replace with each change. I am considering that you do want to store the data in files and not in a DB.

The config file can look like:

<?php
 $config['usd-eur']=1.2;
 $config['usd-gbp']=0.5;
?>

Name this file as config.php,and place it with you scripts then include it.

<?php
 require_once('config.php');
?>

Regarding the $_POST variables you need to escape them to protect yourself from MySQL and XSS attacks.

You can use this function:

<?php
function filter($data) {
$data = trim(htmlentities(strip_tags($data)));
if (get_magic_quotes_gpc())
    $data = stripslashes($data);

$data = mysql_real_escape_string($data);

return $data;
}?>

Then loop through your POST variables:

foreach($_POST as $key => $value) {
 $mydata[$key] = filter($value);
}

Once more thing is the amount of processing you perform to detect the selection for the $fromto variable.

Why not to do it like that:

<select name="fromTo">
  <option value="1">(EUR) ---> (USD)</option>
  <option value="2">(EUR) ---> (GBP)</option>
</select>

Then perform a Switch-Case statement

<?php
 switch($mydata['fromTo']){
  case 1:
   $from='euro';
   $to='usd';
   break;
  case 2:
   $from='euro';
   $to='gbp';
   break;
 }

Hope that helps.