Question

I want to be able to convert from one currency to another, I found a XML API here which covers most of the currencies I use around my site, but the problem I’m experiencing is how to convert from one currency to another with this XML file.

Obviously I parsed and added the currencies and it’s rates to an array like this:

Array 
(
    [USD] => 1.3412
    [JPY] => 107.99
    [BGN] => 1.9558
    ...

The formula to convert from an exchanged rate is this:

$from = 'GBP';  // The currency can be dynamic to a different currency
$to = 'USD';    // this one too

$amount = 400;
$converted_amount = round($amount / $rate, 2);

$rate is what I’m clueless onto what to do – how to convert into the exchange rate that will be able to be dividable to the $amount.

Answer 1

The rates in this XML are actually euro-rates: i.e., EUR/USD, EUR/JPY, etc. So what you need is:

$from = 'USD'; 
$to   = 'JPY';
$amount = 100;

$conversion_rate  = $rates[$from] / $rates[$to];
$converted_amount = round ($amount / $conversion_rate, 2);