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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>&nbsp;</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

Books covering this topic
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Other Examples
This example comes from our "Further Web Page and Network Handling" training module. You'll find a description of the topic and some other closely related examples on the "Further Web Page and Network Handling" module index page.

Full description of the source code
You can learn more about this example on the training courses listed on this page, on which you'll be given a full set of training notes.

Many other training modules are available for download (for limited use) from our download centre under an Open Training Notes License.

Other resources
• Our Solutions centre provides a number of longer technical articles.
• Our Opentalk forum archive provides a question and answer centre.
The Horse's mouth provides a daily tip or thought.
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Purpose of this website
This is a sample program, class demonstration or answer from a training course. It's main purpose is to provide an after-course service to customers who have attended our public private or on site courses, but the examples are made generally available under conditions described below.

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This web site is written and maintained by Well House Consultants.

Conditions of use
Past attendees on our training courses are welcome to use individual examples in the course of their programming, but must check the examples they use to ensure that they are suitable for their job. Remember that some of our examples show you how not to do things - check in your notes. Well House Consultants take no responsibility for the suitability of these example programs to customer's needs.

This program is copyright Well House Consultants Ltd. You are forbidden from using it for running your own training courses without our prior written permission. See our page on courseware provision for more details.

Any of our images within this code may NOT be reused on a public URL without our prior permission. For Bona Fide personal use, we will often grant you permission provided that you provide a link back. Commercial use on a website will incur a license fee for each image used - details on request.

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