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Wednesday, June 04, 2008

One More Use of Web Cookies

One More Use of Web Cookies

Ok, so we were discussing about Cookies in the last post, continuing the discussion today we’ll see one more example of where cookie is almost irreplaceable by any other method.

If you remember the post Creating a Simple Visitor Counter in PHP, although we named it ‘Visitor Counter’, what it actually counted was the number of times a page was requested. So, for example one person can request a page ten times and counter would show ten but actually the number of visitor id ONE. Ten is the number of page views.

Now you may have got what I’m up to today! Yeah we’ll employ cookies to track whether consecutive page requests came form the same visitor or not. If it is then another counter for number of page views will be incremented instead.

We cannot use Session Variables as they by default last only until the session is over. We’ll make the cookie expire after twenty four hour or one day period after that again the first request by a previously visited visitor would rather be counted as a visit and not a page view.

We’re taking the time of twenty four hours as most counters do the same, counting the same visitor as again unique after that time.

To make the counting process more clear, let’s take an example. If I request a website with our counter on, the first time both ‘visitors’ and ‘pageviews’ (we’ll have two counters) would increment. No if I make consecutive requests to the pages, only the ‘pageviews’ counter would increment. Again after 24-hours (cookie expiry, if I request the site again, both the counters would again increment (since I’d be unique for that time) and the process repeats.

Below is the code with enough comments to make the additional part very clear, you can read Creating a Simple Visitor Counter in PHP to see how to integrate this to existing sites.

<?php
/* 
Script: Visitor Counter with Cookies
Filename: counter.php
Date: 4-Jun-08 
Copyright 2008 Arvind Gupta 
http://learning-computer-programming.blogspot.com/ 

Use: Include this file in the web page (PHP) you want to have the Counter on.
     Call 'showCounter();' to show the counter.

You are free to modify, change, publish or do whatever with this script 
as long as this note is intact. Thank You! 
*/ 

//function
function showCounter()
{
    
//open the file in read & write mode
    
$fp=fopen("counter.txt","r+");
    
//fetch data
    //there will be two data in the file
    //first the number of visitors
    //and second pageviews
    
$data=fgets($fp,20);
    
    
//data will be seperated with a ' ' space
    //so breaking it into two seperate values
    
$data=explode(' ',$data);
    
    
//have the sepearte values in variables
    
$visitors=(int)$data[0];
    
$pageloads=(int)$data[1];;
    
    
//if NOT a unique visitor
    
if($_COOKIE['unique']=='no')
        
//increment PAGEVIEWS
        
$pageloads++;
    else
//if first tine visitor (unique in 24 hours)
        
{
            
//increment both VISITORS and PAGEVIEWS
            
$visitors++;
            
$pageloads++;
            
            
//set cookie, because visitor is not unique
            //from now on till 24 hours
            
            //first calculate the expiry time of the cookie
            //mktime generates current time in UNIX time format
            //(in seconds) we add 24*60*60 (no. of seconds in 24 hours)
            //to that
            
$expiry=mktime()+24*60*60;
            
setcookie('unique','no',$expire);
        }
    
    
//seek to the start of file
    
fseek($fp,0);
    
    
//write the new value
    //in the format we have used
    
fputs($fp,$visitors.' '.$pageloads);
    
    
fclose($fp);

    
//printf function is used to pad the 
    //pageload value, to make it look
    //good
    
return (printf("Visitors: <h1><span style=\"color: #fff; background: #000;\">%010d</span></h1>Pageviews:<h1><span style=\"color: #fff; background: #000;\">%010d</span></h1>",$visitors,$pageloads));
}
?>

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