Before we try the class and show a real example, it's necessary to list its full code. This way, you'll have an overall conception of how it works. Here's the complete source code for the "Pager" class:

<?php
/*
* PHP Pager class
* @access public
*/

class Pager {
  /**
  * MySQL connection identifier
  * @access private
  * data type string
  */
  var $conId;

 

  /**
  * SQL query
  * @access private
  * data type string
  */
  var $query;

 

  /**
  * number of records per page
  * @access private
  * data type integer
  */
  var $numRecs;

 

  /**
  * generated output for records and paging links
  * @access private
  * data type string
  */
  var $output;

 

  /**
  * records template file
  * @access private
  * data type string
  */
  var $template;

 

  /** ID attribute for styling paging links
  * @access private
  * data type string
  */
  var $linksId;

 

  /**
  * Pager constructor
  * @access public
  * @param string conId
  * @param string query
  * @param string linksId
  * @param integer numRecs
  * @param string template
  */
  function Pager (&$conId,$query,$linksId,$numRecs=10,
                 $template='default_record_template.htm'){

    // validate connection idenfifier
    (mysql_query('SELECT 1',&$conId))?$this->conId=
     &$conId:die('Invalid connection identifier.');

    // validate query
    (preg_match("/^SELECT/",$query))?$this->query=
     $query:die('Invalid query '.$query);

    // validate paging links ID
    (!is_numeric($linksId))?$this->linksId=
     $linksId:die('Invalid ID for paging links '.$linksId);

    // validate template file
    (file_exists($template))?$this->template=
     $template:die('Invalid template file '.$template);

    // validate number of records per page
    (is_int($numRecs)&&$numRecs>0)?$this->numRecs=
      $numRecs:die('Invalid number of records '.$numRecs);

    // initialize output
    $this->output='';

  }

 

  /**
  * method displayRecords
  * @access public 
  * @return string output
  * @param integer page
  * @description display paginated records/paging links
  */
  function displayRecords($page){

    // calculate total number of records
    if(!$totalRecs=mysql_num_rows(mysql_query($this->query))){
      die('Cannot retrieve records from database');
    }

    // calculate number of pages
    $numPages=ceil($totalRecs/$this->numRecs);
    if(!preg_match("/^\d{1,2}$/",$page)||
       $page<1||$page>$numPages){
      $page=1;
    }

    // get result set
    $result=mysql_query($this->query.' LIMIT '.($page-1)*$this->numRecs.','.$this->numRecs);

    // read template file
    $templateContent=file($this->template);

    // append template file footer to final output
    $this->output=reset($templateContent);

    // move pointer to placeholder line
    $templateRow=next($templateContent);

    // replace placeholders with actual data
    while($row=mysql_fetch_row($result)){
      $tempOutput=$templateRow;
      for($i=0;$i<mysql_num_fields($result);$i++){
         $tempOutput=str_replace('{data'.$i.'}',
          $row[$i],$tempOutput);
      }

      // remove unpopulated placeholders
      $this->output.=preg_replace("/{data.}/",'',$tempOutput);

    }

    // append template file footer to final output
    $this->output.=end($templateContent);

    // create page links
    $this->output.='<div id="'.$this->linksId.'">';

    // create previous link
    if($page>1){
      $this->output.='<a href="'.$_SERVER['PHP_SELF'].'?page='.
      ($page-1).'">&lt;&lt;Previous</a>&nbsp;';
    }

    // create numerated links
    for($i=1;$i<=$numPages;$i++){
      ($i!=$page)?$this->output.='<a href="'.$_SERVER['PHP_SELF']
       .'?page='.$i.'">'.$i.'</a>&nbsp;':
       $this->output.=$i.'&nbsp;';
    }

    // create next link
    if($page<$numPages){
      $this->output.='&nbsp;<a href=
      "'.$_SERVER['PHP_SELF'].'?page=
       '.($page+1).'">Next&gt;&gt;</a> ';
    }
    $this->output.='</div>';

    // return final output
    return $this->output;

  }

}

?>

That was a long listing, don't you think? However, it's really worthwhile. Now we're ready to develop some examples and see the class in action. Since the class will work with the MySQL server, let's begin by setting up a sample database and creating a basic table with some records. Want to know more? Just click the link and keep reading.