Archive for July, 2008

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AdSense Injection WordPress plugin tweaks

Thursday, July 24th, 2008

On this blog I use the AdSense Injection plugin to automatically add Google’s targeted AdSense adverts to my posts. The plugin is excellent and has helped to make more money for this site but there are a few tweaks that I have done.

First, I’ve made a modification so that if a individual post page is shorter than a certain number of characters then the number of adverts is limited to one.

Second, I’ve made a change so instead of looking for ‘<p’ tags to use as AdSense insertion points it looks for the full paragraph tag – ‘<p>’. The reason I did this is because I often include code in my posts in <pre> tags and the AdSense plugin code was inserting adverts in my source code snippets which looked wrong. After making this change the adverts only appear in the text of my posts.

Both sets of changes are shown in the code below. You can simply replace the ai_the_content() function in version 2.0 of the plugin with this version.

adsense-injection.php
function ai_the_content($content){
  global $doing_rss;
  if(is_feed() || $doing_rss)
    return $content;
  if(strpos($content, "<!--noadsense-->") !== false) return $content;

  if(is_home() && get_option('ai_home') == "checked=on") return $content;
  if(is_page() && get_option('ai_page') == "checked=on") return $content;
  if(is_single() && get_option('ai_post') == "checked=on") return $content;
  if(is_category() && get_option('ai_cat') == "checked=on") return $content;
  if(is_archive() && get_option('ai_archive') == "checked=on") return $content;

  global $ai_adsused, $user_level;
  if(get_option('ai_betatest') == "yes" && $user_level < 8)
    return $content;
  if(get_option('ai_notme') == "yes" && $user_level > 8)
    return $content;

  # RML: backup content
  $original_content = $content;

  $numads = get_option('ai_nads');
  if(is_single())
    $numads = get_option('ai_nadspp');

  $content_hold = "";
  if(strpos($content, "<!--adsensestart-->") !== false){
    $content_hold = substr($content, 0, strpos($content, "<!--adsensestart-->"));
    $content = substr_replace($content, "", 0, strpos($content, "<!--adsensestart-->"));
  }

  while($ai_adsused < $numads)
  {
    $poses = array();
    $lastpos = -1;
    # RML: change <p to <p> to stop ads before <pre>
    $repchar = "<p>";
    if(strpos($content, "<p>") === false)
      $repchar = "<br";

    while(strpos($content, $repchar, $lastpos+1) !== false){
      $lastpos = strpos($content, $repchar, $lastpos+1);
      $poses[] = $lastpos;
    }

    //cut the doc in half so the ads don't go past the end of the article.  It could still happen, but what the hell
    $half = sizeof($poses);
    $adsperpost = $ai_adsused+1;
    if(!is_single())
      $half = sizeof($poses)/2;

    while(sizeof($poses) > $half)
      array_pop($poses);

    $pickme = $poses[rand(0, sizeof($poses)-1)];

    $replacewith = ai_pickalign(get_option('ai_lra'));
    $replacewith .= ai_genadcode()."</div>";

    # RML: remove hardcoded length
    $content = substr_replace($content, $replacewith.$repchar, $pickme, strlen($repchar));
    $ai_adsused++;

    # RML: if content is short then limit to one advert
    if(strlen($original_content) < 2500) return $content_hold.$content;

    if(!is_single())
      break;
  }

  return $content_hold.$content;
}

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Adding ‘Related Posts’ to WordPress articles and 404 error pages

Tuesday, July 22nd, 2008

Many blogs have a list of related articles after each of their posts. I wanted something similar for my WordPress blog but found it wasn’t as easy to do as I thought it would be.

At the same time I was interested in capturing any access attempts to non-existant pages (causing a 404 error), and showing a list of suggested links. This is something that is useful to do to turn people who get 404 errors into readers of your blog.

I first looked at the WASABI related post plugin. It did what I wanted with the related entries but it requires you to add a tag to each post where you want the related entries to appear. There is also a version of the plugin which can generate sensible links for any 404 errors. It does this by turning the incorrect URL into a list of terms which are then used to find related posts.

The next plugin that I read about was called ‘Aizattos Related Posts’. This plugin was originally based on WASABI but has evolved since. It inserts related links without needed to add any special tags to the posts. A lot of good feedback was given about this plugin but it seems that the author has removed it from the original download site. Fortunately someone has re-posted this plugin to this site.

I therefore have what I need in two separate plugins. I installed the Aizattos Related Posts plugins and then created a modified version of the WASABI 404 handling code. The 404 handler is in one function ‘related_posts_404′. Below is the modified version of the WASABI code which will work with the Aizattos Related Posts plugin. As well as showing the related links it also shows an extract from the post page. Just put this function in the Aizattos Related Posts plugin PHP file.

related_posts_404()
function related_posts_404($limit=5, $len=50,
	$before_title = '', $after_title = '',
	$before_post = '', $after_post = '',
	$show_pass_post = false, $show_excerpt = true) {

    global $wpdb, $post;

    $before_title   = '<span class="aizatto_related_posts_title" >';
    $after_title    = '</span>';
    $before_excerpt = '<div class="aizatto_related_posts_excerpt">';
    $after_excerpt  = '</div><p></p>';
    $before_related = '<li>';
    $after_related  = '</li>';

    $search_term = $_SERVER['REQUEST_URI'];
    $search = array ('@[\/]+@', '@(\..*)@', '@[\-]+@', '@[\_]+@', '@[\s]+@', '@archives@','@(\?.*)@','/\d/');
    $replace = array (' ', '', ' ', ' ', ' ', '', '','');
    $search_term = preg_replace($search, $replace, $search_term);
    $search_term = trim($search_term);
    $terms = $search_term;

    $time_difference = get_settings('gmt_offset');
    $now = gmdate("Y-m-d H:i:s",(time()+($time_difference*3600)));

    // Primary SQL query
    $sql = "SELECT ID, post_title, post_content,"
         . "MATCH (post_name, post_content) "
         . "AGAINST ('$terms') AS score "
         . "FROM $wpdb->posts WHERE "
         . "MATCH (post_name, post_content) "
         . "AGAINST ('$terms') "
		 . "AND post_date <= '$now' "
         . "AND (post_status IN ( 'publish',  'static' ) && ID != '$post->ID') ";
    if ($show_pass_post=='false') { $sql .= "AND post_password ='' "; }
    $sql .= "ORDER BY score DESC LIMIT $limit";
    $results = $wpdb->get_results($sql);
    $output = '';
    if ($results) {
        foreach ($results as $result) {
            $title = stripslashes(apply_filters('the_title', $result->post_title));
            $permalink = get_permalink($result->ID);
            $output .= $before_title
                .'<a href="'. $permalink .'" rel="bookmark" title="Permanent Link: '
		. $title . '">'
		. $title . '</a>'
		. $after_title;
            if ($show_excerpt=='true') {
                $post_content = strip_tags($result->post_content);
                $post_content = stripslashes($post_content);
                $words=split(" ",$post_content);
                $post_strip = join(" ", array_slice($words,0,$len));
                $output .= $before_excerpt . $post_strip . $after_excerpt;
                }
        }
        echo $output;
    } else {
        echo $before_title.'Fuzzy ...'.$after_title;
    }
}

Although no code modifications are needed for the related links in your normal posts, you will have to make a modification to your theme’s 404 page if you want related links for any ‘Not Found’ errors. In blue below is the modification I made to my 404.php for the default theme.

\blog\wp-content\themes\default\404.php
<?php get_header(); ?>

	<div id="content" class="narrowcolumn">

		<h2 class="center">Error 404 - Not Found</h2>

		<p>We're sorry but the page you are looking
		for isn't at this location. Were you perhaps
		looking for one of these articles?</p>

		<?php related_posts_404(); ?>

	</div>

<?php get_sidebar(); ?>

<?php get_footer(); ?>

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Reverse a linked list – C++ source code

Monday, July 21st, 2008

Reversing a linked list is a simple programming problem, which is often a interview question. In this case I’m referring to a singly linked list. I’ll provide the C++ solution and the C++ test code.

One of the easiest ways to reverse the list is to create a new head pointer, iterate through the list removing each item in turn and then inserting them at the beginning of the new list.

Here is the definition of my linked list node and the code to reverse the list.

class Node
{
public:
	Node(int value) : value(value), next(NULL) {}
public:
	int value;
	Node* next;
};

Node* reverseList(Node* head)
{
	Node* newList = NULL;
	Node* current = head;
	while (current)
	{
		Node* next = current->next;
		current->next = newList;

		newList = current;
		current = next;
	}
	return newList;
}

Below is the code I used to test this. This is what it does:

  1. It creates a simple linked list.
  2. Prints it out – output should be ‘12345′.
  3. Reverses it.
  4. Prints it out – output should be ‘54321′.
  5. Reverses it again.
  6. Prints it – output should be ‘12345′.
  7. Deletes the list.
void listTests()
{
	Node* one = new Node(1);
	Node* two = new Node(2);
	Node* three = new Node(3);
	Node* four = new Node(4);
	Node* five = new Node(5);

	one->next = two;
	two->next = three;
	three->next = four;
	four->next = five;

	Node* head = one;

	printList(head);

	head = reverseList(head);
	printList(head);

	head = reverseList(head);
	printList(head);

	// cleanup memory
	Node* current = head;
	while (current)
	{
		Node* next = current->next;
		delete current;
		current = next;
	}
}

void printList(Node* head)
{
	Node* current = head;
	while (current)
	{
		cout << current->value;
		current = current->next;
	}
	cout << endl;
}

This should be the output:

12345
54321
12345

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