Exchange rate convertor

Further Web Page and Network Handling example from a Well House Consultants training course
More on Further Web Page and Network Handling [link]

This example is described in the following article(s):
• Hot answers in PHP - [link]
• Questions I have been asked on answering the phone - [link]

This example references the following resources:
http://www.ecb.int/stats/eurofxref/eurofxref-daily.xml
http://www.wellho.net/course/ph.html

Source code: exchange.php Module: H112

<html><head><title>Current Exchange Rate Demo</title><</head>
<body><h2>Exchange rate demo</h2>
This demonstration program shows you how you can grab a file from
another web site (in this example, the European Central Bank) and
use it within your own page. Exchange rates are updated daily;
using the code in this page, we can maintain our information
automatically.<br><br>
Caution - this is an example. We are not responsible for the rates
quoted which you MUST check yourself. You must also check that you
are allowed by law to grab information of another web site before
you do so in your own application. The <a href=http://www.ecb.int>ECB
site</a> is declared as a
feed of public information, but that doesn't apply to many sites and
you'll need to check copyright issues, etc.<br><br>
<?php

$now = time();
$cache = "$_SERVER[DOCUMENT_ROOT]/../include/erates.xml";
$exchrate[EUR] = 1.00;
$amount = 1000;

# Exchange rates - Grab current rates from European Central Bank

# Check whether we have a recent copy of the data locally

if (($interval = $now - filemtime($cache)) > 3600 * 2) {
        $stuff = file("http://www.ecb.int/stats/eurofxref/eurofxref-daily.xml");
        $trace = "Cache REFRESHED after $interval seconds";
        $fh = fopen ($cache,"w");
        foreach ($stuff as $line) {
                fputs($fh,$line);
                }
} else {
        $stuff = file($cache);
        $trace = "Cached information reused aged $interval seconds";
        }

# Currency names that we'll use later on

$names = array (USD => "US Dollar",
        JPY => "Japanese Yen",
        DKK => "Danish Krone",
        GBP => "Pound Sterling",
        SEK => "Swedish Krona",
        CHF => "Swiss Franc",
        ISK => "Icelandic Krona",
        NOK => "Norwegian Krone",
        BGN => "Bulgarian Lev",
        CYP => "Cyprus Pound",
        CZK => "Czech Koruna",
        EEK => "Estonian Kroon",
        HUF => "Hungarian Forint",
        LTL => "Lithuanian Litas",
        LVL => "Latvian Lats",
        MTL => "Maltese Lira",
        PLN => "Polish Zloty",
        ROL => "Romanian Leu",
        SIT => "Slovenian Tolar",
        SKK => "Slovakian Koruna",
        TRL => "Old Turkish Lira (to 2004)",
        TRY => "New Turkish Lira (2005)",
        AUD => "Australian Dollar",
        CAD => "Canadian Dollar",
        HKD => "Hong Kong Dollar",
        NZD => "New Zealand Dollar",
        SGD => "Singapore Dollar",
        KRW => "South Korean Won",
        EUR => "European Euro",
        ZAR => "South African Rand");

# Extract data from page - conversion rates between each currency and the Euro

foreach ($stuff as $line) {
        ereg("currency='([[:alpha:]]+)'",$line,$gota);
        if (ereg("rate='([[:graph:]]+)'",$line,$gotb)) {
                $exchrate[$gota[1]] = $gotb[1];
                }
        }

# Sample output - a table showing an amount converted to Euros, Pounds and Dollars

print ("<b>Conversion to Euros, Pounds, US Dollars from other currencies</b><br>");
print ("<center><table cellpadding=5><tr><td> </td><th>Euros</th><th>Pounds</th><th>Dollars</th></tr>");
foreach (array_keys($exchrate) as $to) {
        if ($names[$to] == "") $names[$to] = $to;
        print ("<tr><td>$amount $names[$to] is about </td>");
        foreach (array("EUR","GBP","USD") as $from) {
                $convertsto = sprintf("%.2f",
                $amount * $exchrate[$from] / $exchrate[$to]);
                print ("<td align=right>$convertsto</td>");
                }
        print ("<tr>");
}
print ("</table></center>");
?>
<hr>
Programmer's feedback: <?= $trace ?><br>
Want to <a href=http://www.wellho.net/course/ph.html>learn
how to write a page like this?</a><br>
Copyright <a href=http://www.wellho.net>Well House Consultants</a>,
<?= date("Y") ?>
</body>
</html>

Learn about this subject

This module and example are covered on the following public courses:
* Learning to program in PHP
* PHP Programming
* PHP Programming
* Learning to program in PHP
Also available on on site courses for larger groups

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