Zeichen ersetzen

// @session_start();

function start()
{
    //This is the directory route to the folder
	$directory="./images/image_random/header/";  

	if (!$_SESSION['PicFilename'])  
	{
	         $dir=opendir( $directory );

	         //This is a relative link to the directory if it is not in the same directory as the file you are displaying the images on

	         $pattern="\.(gif|jpg|jpeg|png|bmp|swf)$";  
	         if(!$dir)
	         {
	         	die("Fehler, kein Bild vorhanden oder php-Fehler");  
	         }
	         $s=readdir($dir);
	         $count="0";  
	         $image;
	         while($s)
	         {
	         	if(ereg($pattern, $s))
	         	{
	         	$image[$count]=$s;
	         	$count++;
	         	}
	         	$s=readdir($dir);
	         }
	         closedir($dir);
                  // Ausgabe
	         $limit=count($image);
	         $limit--;
	         $randNum=rand(0,$limit);
	         $size=getimagesize("$directory$image[$randNum]");  

			 $_SESSION['PicFilename'] 	= $image[ $randNum ];  
			 $_SESSION['PicSize']		= $size[ 3 ];  
	}

	// building the img-tag; first creating a template string for a later replacing with real values
         // aus originalem Link "{SIZE}" entfernt 
	$imgTemplate = "<img src=\"{SOURCE}\" alt=\"Zufallsbild aus Dresden: {IMGNAME}\" border=\"0\" width=\"953px\"/>";  

	// building the search patterns including key values of the template string
	$searchPattern = 	array( '{SOURCE}', '{SIZE}', '{IMGNAME}' );  
	$replacePattern = 	array( 	$directory . $_SESSION['PicFilename'],  
								$_SESSION['PicSize'],  
								$_SESSION['PicFilename'] );  

	$imgLink = str_replace( $searchPattern, $replacePattern, $imgTemplate );
         echo $imgLink; 
}