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In the exercise that follows you create a simple affiliate page named

aff_test.php

. When this script

will be loaded with an

aff_id

query string parameter, you’ll retain the affiliate ID value, then remove

the

aff_id

parameter and do a 301 redirect to the new URL.

When removing query string parameters, special care needs to be taken not to alter the already existing

parameters, so you’ll create a few specialized functions that perform these tasks.

Redirecting Dynamic Affiliate URLs

1.

Create a new file named

url_utils.inc.php

in your

seophp/include

folder, and type this

code in:

<?php

// transforms a query string into an associative array

function parse_query_string($query_string)

{

// split the query string into individual name-value pairs

$items = explode(‘&‘, $query_string);

// initialize the return array

$qs_array = array();

// create the array

foreach($items as $i)

{

// split the name-value pair and save the elements to $qs_array

$pair = explode(‘=’, $i);

$qs_array[urldecode($pair[0])] = urldecode($pair[1]);

}

// return the array

return $qs_array;

}

// removes a parameter from the query string

function remove_query_param($url, $param)

{

// extract the query string from $url

$tokens = explode(‘?’, $url);

$url_path = $tokens[0];

$query_string = $tokens[1];

// transform the query string into an associative array

$qs_array = parse_query_string($query_string);

// remove the $param element from the array

unset($qs_array[$param]);

// create the new query string by joining the remaining parameters

$new_query_string = ‘’;

if ($qs_array)

{

foreach ($qs_array as $name => $value)

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Chapter 5: Duplicate Content

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