PHP - Displaying Google Pagerank

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What is Google PageRank?
PageRank is a numeric value that represents how important a page is on the web. It is Google's way of measuring the importance of web site.




Here is how Google explains PageRank:

PageRank relies on the uniquely democratic nature of the web by using its vast link structure as an indicator of an individual page's value. Google interprets a link from page A to page B as a vote, by page A, for page B. But Google looks at more than the sheer volume of votes, or links a page receives; it also analyzes the page that casts the vote. Votes cast by pages that are themselves "important" weigh more heavily and help to make other pages "important."

Google PageRank is mostly discussed by SEO's but also webmasters, web advertisers and publishers. For example, webmasters will not exchange links with websites whose PageRank is less then 4 or 5. Often, web publishers will pay less money for ads on websites with lower PageRanks. So how do you know what a PageRank of a website is? Simplest way to do it is to install Google toolbar.

Below is modified version of that script. I used the code to create a PHP class that can be easily implemented with your projects.

pagerank.php
<?php
define('GOOGLE_MAGIC', 0xE6359A60);
class pageRank{
var $pr;
function zeroFill($a, $b){
$z = hexdec(80000000);
if ($z & $a){
$a = ($a>>1);
$a &= (~$z);
$a |= 0x40000000;
$a = ($a>>($b-1));
}else{
$a = ($a>>$b);
}
return $a;
}

function mix($a,$b,$c) {
$a -= $b; $a -= $c; $a ^= ($this->zeroFill($c,13));
$b -= $c; $b -= $a; $b ^= ($a<<8);
$c -= $a; $c -= $b; $c ^= ($this->zeroFill($b,13));
$a -= $b; $a -= $c; $a ^= ($this->zeroFill($c,12));
$b -= $c; $b -= $a; $b ^= ($a<<16);
$c -= $a; $c -= $b; $c ^= ($this->zeroFill($b,5));
$a -= $b; $a -= $c; $a ^= ($this->zeroFill($c,3));
$b -= $c; $b -= $a; $b ^= ($a<<10);
$c -= $a; $c -= $b; $c ^= ($this->zeroFill($b,15));
return array($a,$b,$c);
}

function GoogleCH($url, $length=null, $init=GOOGLE_MAGIC) {
if(is_null($length)) {
$length = sizeof($url);
}
$a = $b = 0x9E3779B9;
$c = $init;
$k = 0;
$len = $length;
while($len >= 12) {
$a += ($url[$k+0] +($url[$k+1]<<8) +($url[$k+2]<<16) +($url[$k+3]<<24));
$b += ($url[$k+4] +($url[$k+5]<<8) +($url[$k+6]<<16) +($url[$k+7]<<24));
$c += ($url[$k+8] +($url[$k+9]<<8) +($url[$k+10]<<16)+($url[$k+11]<<24));
$mix = $this->mix($a,$b,$c);
$a = $mix[0]; $b = $mix[1]; $c = $mix[2];
$k += 12;
$len -= 12;
}
$c += $length;
switch($len){
case 11: $c+=($url[$k+10]<<24);
case 10: $c+=($url[$k+9]<<16);
case 9 : $c+=($url[$k+8]<<8);
/* the first byte of c is reserved for the length */
case 8 : $b+=($url[$k+7]<<24);
case 7 : $b+=($url[$k+6]<<16);
case 6 : $b+=($url[$k+5]<<8);
case 5 : $b+=($url[$k+4]);
case 4 : $a+=($url[$k+3]<<24);
case 3 : $a+=($url[$k+2]<<16);
case 2 : $a+=($url[$k+1]<<8);
case 1 : $a+=($url[$k+0]);
}
$mix = $this->mix($a,$b,$c);
/* report the result */
return $mix[2];
}

//converts a string into an array of integers containing the numeric value of the char

function strord($string) {
for($i=0;$i<strlen($string);$i++) {
$result[$i] = ord($string{$i});
}
return $result;
}

function printrank($url){
$ch = "6".$this->GoogleCH($this->strord("info:" . $url));

$fp = fsockopen("www.google.com", 80, $errno, $errstr, 30);
if (!$fp) {
echo "$errstr ($errno)<br />\n";
} else {
$out = "GET /search?client=navclient-auto&ch=" . $ch . "&features=Rank&q=info:" . $url . " HTTP/1.1\r\n" ;
$out .= "Host: www.google.com\r\n" ;
$out .= "Connection: Close\r\n\r\n" ;
fwrite($fp, $out);
while (!feof($fp)) {
$data = fgets($fp, 128);
$pos = strpos($data, "Rank_");
if($pos === false){
}else{
$pagerank = substr($data, $pos + 9);
$this->pr_image($pagerank);
}
}
fclose($fp);
}
}
//display pagerank image. Create some images for the script. If you make your own make sure to call them pr0.gif, pr1.gif, pr2.gif etc.
function pr_image($pagerank){
$this->pr = "<img src=\"images/pr".$pagerank.".gif\" alt=\"PageRank ".$pagerank." out of 10\">" ;
}
function get_pr(){
return $this->pr;
}
}
?>

Usage
Do following:

1. Save the code above as pagerank.php.
2. Download or create your own images to display each rank.
3. Create a directory "images" containing all page rank images.
4. See code below on how to use the class.

<?php
include("pagerank.php");
$gpr = new pageRank();
$gpr->printrank("http://www.yahoo.com");
//display image
echo $gpr->get_pr();
?>


UPDATE:
Some servers calculate the checksum differently which makes the script unusable. If the script doesn't work for you test the script on a server that does it correctly and get the result that way.

Also see our free scripts section, where we have a number of free ready made scripts for displaying Pagerank, Backlinks, Alexa, Yahoo & MSN results.

Plus if you just want to display your sites current PR to your visitors, we also have a simple piece of code you can add to your webpage which will display a small graphic with the PR. Whenever Google updates it's PR, the graphic will automatically update as well meaning you never have to do anything again as the PR displayed will always be current.