php - Smart pagination algorithm

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Answer 1

I had the same need a while ago.

Here's the article I used to get it done (with PHP code): Digg-Style Pagination

It works pretty fast and has some additions to what you're trying to do, like:

[1] 2 3 4 5 6 ... 100
1 [2] 3 4 5 6 ... 100
...
1 ... 4 5 [6] 7 8 ... 100

Here is the code from the broken link:

<?php
    /*
        Place code to connect to your DB here.
    */

    // How many adjacent pages should be shown on each side?
    $adjacents = 3;

    /* 
       First get total number of rows in data table. 
       If you have a WHERE clause in your query, make sure you mirror it here.
    */
    $query = "SELECT COUNT(*) as num FROM portfolio";
    $total_pages = mysql_fetch_array(mysql_query($query));
    $total_pages = $total_pages[num];

    /* Setup vars for query. */
    $limit = 2;                                 //how many items to show per page
    if($page) 
        $start = ($page - 1) * $limit;          //first item to display on this page
    else
        $start = 0;                             //if no page var is given, set start to 0

    /* Get data. */
    $query = "SELECT category, uname, title FROM portfolio LIMIT $start, $limit";
    $portfolio = mysql_query($query);

    /* Setup page vars for display. */
    if ($page == 0) $page = 1;                  //if no page var is given, default to 1.
    $prev = $page - 1;                          //previous page is page - 1
    $next = $page + 1;                          //next page is page + 1
    $lastpage = ceil($total_pages/$limit);      //lastpage is = total pages / items per page, rounded up.
    $lpm1 = $lastpage - 1;                      //last page minus 1

    /* 
        Now we apply our rules and draw the pagination object. 
        We're actually saving the code to a variable in case we want to draw it more than once.
    */
    $pagination = "";
    if($lastpage > 1)
    {   
        $pagination .= "<div class=""pagination"">";
        //previous button
        if ($page > 1) 
            $pagination.= "<a href=""diggstyle.php?page=$prev"">? previous</a>";
        else
            $pagination.= "<span class=""disabled"">? previous</span>";   

        //pages 
        if ($lastpage < 7 + ($adjacents * 2))   //not enough pages to bother breaking it up
        {   
            for ($counter = 1; $counter <= $lastpage; $counter++)
            {
                if ($counter == $page)
                    $pagination.= "<span class=""current"">$counter</span>";
                else
                    $pagination.= "<a href=""diggstyle.php?page=$counter"">$counter</a>";                 
            }
        }
        elseif($lastpage > 5 + ($adjacents * 2))    //enough pages to hide some
        {
            //close to beginning; only hide later pages
            if($page < 1 + ($adjacents * 2))        
            {
                for ($counter = 1; $counter < 4 + ($adjacents * 2); $counter++)
                {
                    if ($counter == $page)
                        $pagination.= "<span class=""current"">$counter</span>";
                    else
                        $pagination.= "<a href=""diggstyle.php?page=$counter"">$counter</a>";                 
                }
                $pagination.= "...";
                $pagination.= "<a href=""diggstyle.php?page=$lpm1"">$lpm1</a>";
                $pagination.= "<a href=""diggstyle.php?page=$lastpage"">$lastpage</a>";       
            }
            //in middle; hide some front and some back
            elseif($lastpage - ($adjacents * 2) > $page && $page > ($adjacents * 2))
            {
                $pagination.= "<a href=""diggstyle.php?page=1"">1</a>";
                $pagination.= "<a href=""diggstyle.php?page=2"">2</a>";
                $pagination.= "...";
                for ($counter = $page - $adjacents; $counter <= $page + $adjacents; $counter++)
                {
                    if ($counter == $page)
                        $pagination.= "<span class=""current"">$counter</span>";
                    else
                        $pagination.= "<a href=""diggstyle.php?page=$counter"">$counter</a>";                 
                }
                $pagination.= "...";
                $pagination.= "<a href=""diggstyle.php?page=$lpm1"">$lpm1</a>";
                $pagination.= "<a href=""diggstyle.php?page=$lastpage"">$lastpage</a>";       
            }
            //close to end; only hide early pages
            else
            {
                $pagination.= "<a href=""diggstyle.php?page=1"">1</a>";
                $pagination.= "<a href=""diggstyle.php?page=2"">2</a>";
                $pagination.= "...";
                for ($counter = $lastpage - (2 + ($adjacents * 2)); $counter <= $lastpage; $counter++)
                {
                    if ($counter == $page)
                        $pagination.= "<span class=""current"">$counter</span>";
                    else
                        $pagination.= "<a href=""diggstyle.php?page=$counter"">$counter</a>";                 
                }
            }
        }

        //next button
        if ($page < $counter - 1) 
            $pagination.= "<a href=""diggstyle.php?page=$next"">next ?</a>";
        else
            $pagination.= "<span class=""disabled"">next ?</span>";
        $pagination.= "</div>
";       
    }
?>
<ul>
    <?php
        while($item = mysql_fetch_array($portfolio))
        {
    ?>
        <li><a href="/web/20080709045706/http://www.strangerstudios.com/portfolio//"></a></li>
    <?php
        }
    ?>
</ul>
<?=$pagination?>