There are many different traffic analysis tools, ranging from simple counters to complete traffic analyzers. Although there are some free ones, most of them come with a price tag. Why not do it yourself? With PHP, you can easily create a log file within minutes. In this article I will show you how!

Getting the information
The most important part is getting the information from your visitor. Thankfully, this is extremely easy to do in PHP (or any other scripting language for that matter). PHP has a special global variable called $_SERVER which contains several environment variables, including information about your visitor. To get all the information you want, simply use the following code:

// Getting the information
$ipaddress = $_SERVER['REMOTE_ADDR'];
$page = "http://{$_SERVER['HTTP_HOST']}{$_SERVER['PHP_SELF']}";
$page .= iif(!empty($_SERVER['QUERY_STRING']), "?{$_SERVER['QUERY_STRING']}", "");
$referrer = $_SERVER['HTTP_REFERER'];
$datetime = mktime();
$useragent = $_SERVER['HTTP_USER_AGENT'];
$remotehost = @getHostByAddr($ipaddress);

As you can see the majority of information comes from the $_SERVER variable. The mktime() (http://nl2.php.net/mktime) and getHostByAddr() (http://nl2.php.net/manual/en/function.gethostbyaddr.php) functions are used to get additional information about the visitor.

Note: I used a function in the above example called iif(). You can get this function at http://www.phpit.net/code/iif-function.

Logging the information
Now that you have all the information you need, it must be written to a log file so you can later look at it, and create useful graphs and charts. To do this you need a few simple PHP function, like fopen (http://www.php.net/fopen) and fwrite (http://www.php.net/fwrite).

The below code will first create a complete line out of all the information. Then it will open the log file in “Append” mode, and if it doesn’t exist yet, create it.

If no errors have occurred, it will write the new logline to the log file, at the bottom, and finally close the log file again.

// Create log line
$logline = $ipaddress . '|' . $referrer . '|' . $datetime . '|' . $useragent . '|' . $remotehost . '|' . $page . "
";

// Write to log file:
$logfile = '/some/path/to/your/logfile.txt';

// Open the log file in "Append" mode
if (!$handle = fopen($logfile, 'a+')) {
die("Failed to open log file");
}

// Write $logline to our logfile.
if (fwrite($handle, $logline) === FALSE) {
die("Failed to write to log file");
}

fclose($handle);

Now you’ve got a fully function logging module. To start tracking visitors on your website simply include the logging module into your pages with the include() function (http://www.php.net/include):

include ('log.php');

Okay, now I want to view my log file
After a while you’ll probably want to view your log file. You can easily do so by simply using a standard text editor (like Notepad on Windows) to open the log file, but this is far from desired, because it’s in a hard-to-read format.

Let’s use PHP to generate useful overviews for is. The first thing that needs to be done is get the contents from the log file in a variable, like so:

// Open log file
$logfile = "G:projectsphpitcontentrack your visitors using phplog.txt";

if (file_exists($logfile)) {

$handle = fopen($logfile, "r");
$log = fread($handle, filesize($logfile));
fclose($handle);
} else {
die ("The log file doesn't exist!");
}

Now that the log file is in a variable, it’s best if each logline is in a separate variable. We can do this using the explode() function (http://www.php.net/explode), like so:

// Seperate each logline
$log = explode("
", trim($log));

After that it may be useful to get each part of each logline in a separate variable. This can be done by looping through each logline, and using explode again:

// Seperate each part in each logline
for ($i = 0; $i < count($log); $i++) {
$log[$i] = trim($log[$i]);
$log[$i] = explode('|', $log[$i]);
}

Now the complete log file has been parsed, and we’re ready to start generating some interesting stuff.

The first thing that is very easy to do is getting the number of pageviews. Simply use count() (http://www.phpit.net/count) on the $log array, and there you have it;

echo count($log) . " people have visited this website.";

You can also generate a complete overview of your log file, using a simple foreach loop and tables. For example:

// Show a table of the logfile
echo '<table>';
echo '<th>IP Address</th>';
echo '<th>Referrer</th>';
echo '<th>Date</th>';
echo '<th>Useragent</th>';
echo '<th>Remote Host</th>';

foreach ($log as $logline) {
echo '<tr>';

echo '<td>' . $logline['0'] . '</td>';
echo '<td>' . urldecode($logline['1']) . '</td>';
echo '<td>' . date('d/m/Y', $logline['2']) . '</td>';
echo '<td>' . $logline['3'] . '</td>';
echo '<td>' . $logline['4'] . '</td>';

echo '</tr>';

}

echo '</table>';

You can also use custom functions to filter out search engines and crawlers. Or create graphs using PHP/SWF Charts (http://www.maani.us/charts/index.php). The possibilities are endless, and you can do all kinds of things!

In Conclusion…
In this article I have shown you have to create a logging module for your own PHP website, using nothing more than PHP and its built-in functions. To view the log file you need to parse it using PHP, and then display it in whatever way you like. It is up to you to create a kick-ass traffic analyzer.

If you still prefer to use a pre-built traffic analyzer, have a look at http://www.hotscripts.com.

About the Author

Dennis Pallett is a young tech writer, with much experience in ASP, PHP and other web technologies. He enjoys writing, and has written several articles and tutorials. To find more of his work, look at his websites: http://www.phpit.net, http://www.aspit.net and http://www.ezfaqs.com

Introduction
Cookies have long been used in PHP scripts, and are a very useful function. But what exactly are cookies? Maybe you have used then, but you still don’t know exactly what they are. Or you are completely new to cookies? It doesn’t matter, because in this tutorial I will show you exactly what cookies are, and what they are used for.

Cookies in a nutshell
Cookies are small pieces of information that is stored on the computer of your visitors. Each browser handles it differently, but most simply store the information in a small text file. Internet Explorer has a special folder, which can be found in your C:Windows or C:WindowsSystem32 folder. You can delete all your cookies, by going to the Options and ‘Clearing Cookies’ or deleting them by hand. I don’t recommend this though.

Almost every website uses cookies. If you go to Amazon.com, you will get several cookies. The same goes for CNN.com. Even Google uses cookies! They are extremely useful for (temporarily) storing information. For example, if you have a login system for your visitors, you could save their userid and password (very heavily encrypted!) so they are automatically logged in the next time they visit your website.

Or you could remember their last visit, and highlight everything that is new. And that’s just the beginning.

Using Cookies
Using cookies in PHP is extremely easy. In fact, there is nothing to it, because of PHP’s inbuilt setcookie() function. Have a look at the documentation, and then try the following example:

<?php

// Set a cookie
// Cookie name: name
// Cookie value: Dennis Pallett
// Cookie expire: in 24 hours

setcookie (’name’, ‘Dennis Pallett’, time() + (60*60*24));
?>

If you run the code above, then a cookie will be set. That’s all. The cookie name and value are pretty obvious. The cookie expire is when the cookie expires, or goes away. Simply use the time() function and add the number of seconds you want to have the cookie available to it. In the example I added 60*60*24=86400 seconds, or 24 hours.

If you have looked at the documentation, you probably noticed there are additional arguments. As the documentation says, the path is to limit a cookie to a specific path on your web server. This is often used when you run multiple instances of the same script in separate directories. You can safely omit this argument when it doesn’t matter if the cookie is available site-wide.

There is also the domain argument. This can be used to limit the cookie to a specific sub-domain, e.g. test.example.com. You can also safely ignore this argument, or set it to .example.com (note the beginning period, this is essential!).

Finally, there is also the secure argument. This argument is only used for cookies that are sent over a secure HTTPS connection (SSL). Just ignore this argument, unless you’re working with a secure connection.

One thing that should be mentioned is that cookies must be set, before you display any HTML/text. It’s probably best if you turn on output buffering by putting ob_start() at the top of your page.

Now that you have set a cookie, you probably want to retrieve the value as well. After all, that is the whole point of using cookies. Thankfully, as PHP is ever so easy, you can retrieve the same way as you retrieve a GET value. See the following example to retrieve the value of the previous example:

<?php
echo ‘Your name is ‘ . $_COOKIE['name'];
?>

This should print “Your name is Dennis Pallett”. There’s nothing more to it. It’s just that easy!

Finally, one thing you probably want to do as well is remove cookies. This is as easy as setting them. Simply change the value of the cookie to FALSE, and change the expire date to -3000 seconds. See the following example:

<?php
setcookie (’name’, FALSE, time()-1000);
?>

Checking if cookies are enabled
Before you start using cookies, you must make sure your visitor has cookies enabled. This can be done with a simply PHP checking script. Unfortunately, the PHP page needs to reload to check for cookies. But this can be done very transparently, and your visitor should hardly notice anything.

The following example will first set a test cookie, then reload the page, and finally check whether cookies are enabled.

<?php
error_reporting (E_ALL ^ E_WARNING ^ E_NOTICE);

// Check if cookie has been set or not
if ($_GET['set'] != ‘yes’) {
// Set cookie
setcookie (’test’, ‘test’, time() + 60);

// Reload page
header (”Location: checkcookies.php?set=yes”);
} else {
// Check if cookie exists
if (!empty($_COOKIE['test'])) {
echo “Cookies are enabled on your browser”;
} else {
echo “Cookies are <b>NOT</b> enabled on your browser”;
}
}
?>

Run the code above, and see what the output is. Check if cookies are enabled in your browser. If they’re not enabled, then you can enable them by going to your browser’s options. Unfortunately, this is different from each browser, so I can’t give you exact instructions. But Google can.

Storing Arrays
One feature of cookies that is often missed in articles is the ability to story arrays. Cookies can be used to store multi-dimensional arrays, which can be extremely useful to store data.

Consider the following code;

<?php
setcookie (”name[first]“, “Dennis”, time() + (60*60*24));
setcookie (”name[last]“, “Pallett”, time() + (60*60*24));
?>

You can then display these two cookies using the following code:

<?php
echo “First Name: ” . $_COOKIE['name']['first'];
echo “<br />Last Name: ” . $_COOKIE['name']['last'];
?>

The cookie ‘name’ is an array, and has multiple values. You can even go deeper and have multi-dimensional arrays, e.g. $_COOKIE['name']['test']['something']['value']. You could store whole arrays of data in cookies. But beware that you don’t store too much data, there are certain size limits to cookies.

In Conclusion…
Cookies are really versatile, and can be used for a lot of different purposes. Many websites use cookies, and cookies can really make your website more personalized. Using cookies in PHP isn’t hard at all, and you should be able to use them without any difficulty.

Before actively using cookies in your website, you must check whether the visitor has enabled them in their browser. If they don’t have cookies enabled, you must either redirect to a non-cookies version of your website, or you can make sure your website also works without cookies.

You can download a sample script at http://www.phpit.net/demo/php%20and%20cookies/logger.zip, where cookies are used in a (somewhat) practical way. In this example, there is a logging module, called log.php and a display module, called history.php. Basically, you include the log.php in other PHP pages, and then you can view history.php to lookup all the pages you have viewed and how often. The example uses arrays, and stores them in cookies.

The examples in this article can be downloaded at http://www.phpit.net/demo/php%20and%20cookies/examples.zip.

If you have a really unique practical way of using cookies, please let me know at dennis [AT] nocertainty [DOT] com. I’d really like to hear about interesting ways of using cookies.

About the Author

Dennis Pallett is a young tech writer, with much experience in ASP, PHP and other web technologies. He enjoys writing, and has written several articles and tutorials. To find more of his work, look at his websites at http://www.phpit.net, http://www.aspit.net and http://www.ezfaqs.com

by Dennis Pallett
What are Regular Expressions?
A regular expression is a pattern that can match various text strings. Using regular expressions you can find (and replace) certain text patterns, for example “all the words that begin with the letter A” or “find only telephone numbers”. Regular expressions are often used in validation classes, because they are a really powerful tool to verify e-mail addresses, telephone numbers, street addresses, zip codes, and more.

In this tutorial I will show you how regular expressions work in PHP, and give you a short introduction on writing your own regular expressions. I will also give you several example regular expressions that are often used.
Regular Expressions in PHP
Using regex (regular expressions) is really easy in PHP, and there are several functions that exist to do regex finding and replacing. Let’s start with a simple regex find.

Have a look at the documentation of the preg_match function. As you can see from the documentation, preg_match is used to perform a regular expression. In this case no replacing is done, only a simple find. Copy the code below to give it a try.

<?php

// Example string
$str = "Let's find the stuff <bla>in between</bla> these two previous brackets";

// Let's perform the regex
$do = preg_match("/<bla>(.*)</bla>/", $str, $matches);

// Check if regex was successful
if ($do = true) {
// Matched something, show the matched string
echo htmlentities($matches['0']);

// Also how the text in between the tags
echo '<br />' . $matches['1'];
} else {
// No Match
echo "Couldn't find a match";
}

?>

After having run the code, it’s probably a good idea if I do a quick run through the code. Basically, the whole core of the above code is the line that contains the preg_match. The first argument is your regex pattern. This is probably the most important. Later on in this tutorial, I will explain some basic regular expressions, but if you really want to learn regular expression then it’s best if you look on Google for specific regular expression examples.

The second argument is the subject string. I assume that needs no explaining. Finally, the third argument can be optional, but if you want to get the matched text, or the text in between something, it’s a good idea to use it (just like I used it in the example).
The preg_match function stops after it has found the first match. If you want to find ALL matches in a string, you need to use the preg_match_all function. That works pretty much the same, so there is no need to separately explain it.

Now that we’ve had finding, let’s do a find-and-replace, with the preg_replace function. The preg_replace function works pretty similar to the preg_match function, but instead there is another argument for the replacement string. Copy the code below, and run it.

<?php

// Example string
$str = "Let's replace the <bla>stuff between</bla> the bla brackets";

// Do the preg replace
$result = preg_replace ("/<bla>(.*)</bla>/", "<bla>new stuff</bla>", $str);

echo htmlentities($result);
?>

The result would then be the same string, except it would now say ‘new stuff’ between the bla tags. This is of course just a simple example, and more advanced replacements can be done.

You can also use keys in the replacement string. Say you still want the text between the brackets, and just add something? You use the $1, $2, etc keys for those. For example:

<?php

// Example string
$str = "Let's replace the <bla>stuff between</bla> the bla brackets";

// Do the preg replace
$result = preg_replace ("/<bla>(.*)</bla>/", "<bla>new stuff (the old: $1)</bla>", $str);

echo htmlentities($result);
?>

This would then print “Let’s replace the new stuff (the old: stuff between) the bla brackets”. $2 is for the second “catch-all”, $3 for the third, etc.

That’s about it for regular expressions. It seems very difficult, but once you grasp it is extremely easy yet one of the most powerful tools when programming in PHP. I can’t count the number of times regex has saved me from hours of coding difficult text functions.

An Example
What would a good tutorial be without some real examples? Let’s first have a look at a simple e-mail validation function. An e-mail address must start with letters or numbers, then have a @, then a domain, ending with an extension. The regex for that would be something like this: ^[a-zA-Z0-9_.-]+@[a-zA-Z0-9-]+.[a-zA-Z0-9-.]+$

Let me quickly explain that regex. Basically, the first part says that it must all be letters or numbers. Then we get the @, and after that there should be letters and/or numbers again (the domain). Finally we check for a period, and then for an extension. The code to use this regex looks like this:

<?php

// Good e-mail
$good = "john@example.com";

// Bad e-mail
$bad = "blabla@blabla";

// Let's check the good e-mail
if (preg_match("/^[a-zA-Z0-9_.-]+@[a-zA-Z0-9-]+.[a-zA-Z0-9-.]+$/", $good)) {
echo "Valid e-mail";
} else {
echo "Invalid e-mail";
}

echo '<br />';

// And check the bad e-mail
if (preg_match("/^[a-zA-Z0-9_.-]+@[a-zA-Z0-9-]+.[a-zA-Z0-9-.]+$/", $bad)) {
echo "Valid e-mail";
} else {
echo "Invalid e-mail";
}

?>

The result of this would be “Valid E-mail. Invalid E-mail”, of course. We have just checked if an e-mail address is valid. If you wrap the above code in a function, you’ve got yourself a e-mail validation function. Keep in mind though that the regex isn’t perfect: after all, it doesn’t check whether the extension is too long, does it? Because I want to keep this tutorial short, I won’t give the full fledged regex, but you can find it easily via Google.

Another Example
Another great example would be a telephone number. Say you want to verify telephone numbers and make sure they were in the correct format. Let’s assume you want the numbers to be in the format of xxx-xxxxxxx. The code would look something like this:

<?php

// Good number
$good = "123-4567890";

// Bad number
$bad = "45-3423423";

// Let's check the good number
if (preg_match("/d{3}-d{7}/", $good)) {
echo "Valid number";
} else {
echo "Invalid number";
}

echo '<br />';

// And check the bad number
if (preg_match("/d{3}-d{7}/", $bad)) {
echo "Valid number";
} else {
echo "Invalid number";
}

?>

The regex is fairly simple, because we use d. This basically means “match any digit” with the length behind it. In this example it first looks for 3 digits, then a ‘-’ (hyphen) and finally 7 digits. Works perfectly, and does exactly what we want.

What exactly is possible with Regular Expressions?
Regular expressions are actually one of the most powerful tools in PHP, or any other language for that matter (you can use it in your mod_rewrite rules as well!). There is so much you can do with regex, and we’ve only scratched the surface in this tutorial with some very basic examples.

If you really want to dig into regex I suggest you search on Google for more tutorials, and try to learn the regex syntax. It isn’t easy, and there’s quite a steep learning curve (in my opinion), but the best way to learn is to go through a lot of examples, and try to translate them in plain English. It really helps you learn the syntax.

In the future I will dedicate a complete article to strictly examples, including more advanced ones, without any explanation. But for now, I can only give you links to other tutorials:
The 30 Minute Regex Tutorial
Regular-Expressions.info

About the Author

Dennis Pallett is a young tech writer, with much experience in ASP, PHP and other web technologies. He enjoys writing, and has written several articles and tutorials. To find more of his work, look at his websites at http://www.phpit.net, http://www.aspit.net and http://www.webdev-articles.com

using include files
Include files

This tutorial shows how to use the include() function.

The include() function can be used to call an external file from your server or even a different server.

Syntax

The general syntax for a basic include is as follows

<?php include(”otherfile.txt”); ?>

This includes a file called otherfile.txt from the same directory on your server.

You can also use it like this

<?php include(”http//www.myothersite/otherfile.txt”); ?>

This means you can share the same file on more than one site .

Advantages

Well the advantages are obvious if you are site is growing. Imagine you have a site with 50 pages and you have designed a nice
navigation area but you have forgotten a download link. This would require 50 changes to your site but using an template with an
include file you would change the include file content and all the other pages would be updated

Basic Math Operators

The basic math operators in PHP should be familiar to anyone with programming experience . The set of mathematical operators available are listed below.

Operator	Description
+	The addition operator
-	The subtraction operator , can also be used for negation like this -9
*	The multiplication operator
/	the division operator
%	the modulus operator , returns the remainder after division . For example 25 % 3 would give us 1 .

Here is an example

<?php
$number1 = 9;
$number2 = 4;
echo $number1 + $number2;
?>

Which produces the following
13

Incrementing

To increment a variable in PHP we do the following

$yearsindebt++;

This increments the $yearsindebt variable by one , we can also do the following .

$mybill += 20;

which is the same as saying $mybill = $mybill + 20;

Order Of Precedence

The math operators all have to obey an order of precedence which is used in mathematics . This often catches out beginners . Lets look at an example

$calc = 25 + 4 * 2;

What do you think the value of $calc is , well you could add 25 + 4 and get 29 then multiply by 2 and get 58 . Wrong . The rules of precedence say that multiplication gets calculated before addition so you get 4 * 2 is 8 and then 25 + 8 = 33 . 33 is the correct answer . A big difference from 58 .

At school I was taught to use BODMAS to help remember order of precedence this is basically Brackets , Division , Multiplication , Addition , Subtraction. What if you want to add the 25 + 4 first and then multiply this by 2 , well you can do the following.

$calc = (25 + 4) * 2;

Now the brackets get evaluated first because they come before multiplication in the order of precedence..