Grady Laksmono

interface hasArea {
	public function getArea();
}

class Rectangle implements hasArea {
	static $w;
	static $l;
	public function __construct($w, $l) {
		$this->w = $w;
		$this->l = $l;
	}

	public function getArea() {
		return $this->w * $this->l;
	}
}

class Square extends Rectangle {
	public function setWidth($w) {
		parent::$w = $w;
	}

	public function setLength($l) {
		parent::$l = $l;
	}

	public function getArea() {
		return parent::$w * parent::$l;
	}

	public function getArea2() {
		return $this->w * $this->l;
	}
}

$rect = new Rectangle(10, 5);
print $rect->getArea();
print "";
$sqr = new Square(5, 5);
print $sqr->getArea();
print "";
print $sqr->getArea2();
print "";
$sqr->setWidth(10);
$sqr->setLength(10);
print $sqr->getArea();

/*
	Output:
	50
	0
	25
	100
*/

PHP supports inheritance and polymorphism. The above is one tiny example when I played around with it. If you see the output, you realize that setWidth and setLength would set the parent variable, in which is NOT set even I’ve instantiated Rectangle using $w and $l parameter on its constructor.

config.php

$username = 'username';
$password = 'password';
$database = 'dbname';
$table = 'dbtable';
$host = 'localhost';

$rowsPerPage = 10;
$pageNum = 1;

opendb.php

include('config.php');
$link = mysql_connect($host, $username, $password);
if (!$link) {
	die('Could not connect: ' . mysql_error());
}
mysql_select_db($database);

closedb.php

include('config.php');
mysql_close($link);

index.php

include('opendb.php');

// if $_GET['page'] defined, use it as page number
if(isset($_GET['page'])) {
    $pageNum = $_GET['page'];
}

// counting the offset
$offset = ($pageNum - 1) * $rowsPerPage ;

// selecting $rowPerPage, starting from $offset
$query = "SELECT * FROM " . $table . " LIMIT " . $offset . " , " . $rowsPerPage;
$result = mysql_query($query) or die ('Error, query failed');
$totalRows = mysql_num_rows($result);

while($row = mysql_fetch_array($result)) {
   echo $row['fname'] . '';
}

// how many rows we have in database
$query   = "SELECT COUNT(*) AS numRows FROM " . $table;
$result  = mysql_query($query) or die('Error, query failed');
$row     = mysql_fetch_array($result, MYSQL_ASSOC);
$numRows = $row['numRows'];

// how many pages we have when using paging?
$maxPage = ceil($numRows/$rowsPerPage);

// print the link to access each page
$self = $_SERVER['PHP_SELF'];
$nav  = '';

for($page = 1; $page <= $maxPage; $page++) {
   if ($page == $pageNum) {
      $nav .= " " . $page . " "; // no need to create a link to current page
   } else {
      $nav .= " " . $page . " ";
   }
}

// creating previous and next link
// plus the link to go straight to
// the first and last page

if ($pageNum > 1) {
   $page  = $pageNum - 1;
   $prev  = " [Prev] ";

   $first = " [First Page] ";
} else {
   $prev  = ''; // we're on page one, don't print previous link
   $first = ''; // nor the first page link
}

if ($pageNum < $maxPage) {
   $page = $pageNum + 1;
   $next = " [Next] ";

   $last = " [Last Page] ";
} else {
   $next = ''; // we're on the last page, don't print next link
   $last = ''; // nor the last page link
}

// print the navigation link
echo $first . $prev . $nav . $next . $last;

include('closedb.php');

I think the code is pretty straight forward other than understanding on how does the $offset works. Also, I just knew that in PHP you could do something like:

$var = 1;
print("some $var");

That means you could combine both variable and string. PHP takes care to differentiate between the real string and variable. So, you don’t have to do all of the complicated stuff by adding dots as you see in my code. However, I always like to make it explicit.. :).. As you see in this code that I’m still using dots all around, well, it does get more complicated when you’re dealing with more variables, but that way my IDE would be able to differentiate between the real variable and string. That means it adds my visibility when looking at the codes.

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