PHP preg_match: linking single or multiple images via class function - php

Question

Hey fellow programmers,
What I'm trying to accomplish is a dynamic way to source images from a directory with the use of a class image.
I'm stuck at supplying an exact string which returns a match but when trying to echo " with the returned match if the whole string is not provided then the image is linked with a partial string plus the extension.
<?php $image = new image; ?>
calling the class function with:
<?php $image -> get_image('this_string_1',''); ?>
The Image directory contents
<?php $path = $_SERVER['DOCUMENT_ROOT'].'/images/;'?>
this_string_1.png
this_string_2.png
this_string_3.png
The class:
<?php
class image{
function get_image($name,$class){
if(strlen($class)==0){ $class="default"; }
####[ Checks the type of image
global $doc_root,$html_path;
if($handle = opendir($doc_root.'/images/')){
while(false !==($value = readdir($handle))){
if($value !== '..' && $value!=='.'){
$extention;
$ext_jpeg = substr($value,-3);
if($ext_jpeg=='jpg'){
$extention=".jpg";
}
$ext_png = substr($value,-3);
if($ext_png=='png'){
$extention=".png";
}
$ext_gif = substr($value,-3);
if($ext_gif=='gif'){
$extention='.gif';
}
}
switch($extention){
case '.jpg':
if(preg_match("/$name/",$value,$result)){
foreach($result as $jpg){
echo '<img class="'.$class.'" src="'.$html_path.'/images/'.$jpg.'.jpg">';
}
}
break;
case '.png':
if(preg_match("/$name/",$value,$result)){
foreach($result as $png){
echo '<img class="'.$class.'" src="'.$html_path.'/images/'.$png.'.png">';
}
}
break;
case '.gif':
if(preg_match("/$name/",$value,$result)){
foreach($result as $gif){
echo '<img class="'.$class.'"src="'.$html_path.'/images/'.$gif.'.gif">';
}
}
break;
}
}
}
}
}
?>
I'm sure there are many ways to accomplish something like this. Any advice would be greatly appreciated.
As per Martins advice.
I have removed the if and switch statements and replaced it with "substr" in the second if statement.
<?php
class image{
function get_image($name,$class){
if(strlen($class)==0){ $class="default"; }
global $doc_root,$html_path;
if($handle = opendir($doc_root.'/images/')){
while(false !==($value = readdir($handle))){
if($value !== '..' && $value!=='.' && substr($value, 0, -4)==$name){
echo '<img src="'.$html_path.'/images/'.$value.'">';
}
}
}
}
}
?>

Answer 1

1) I do not see much point of your sequence of if statements to assign $extention. Why don't you just do $extention = substr($value,-4)?
2) The switch($extention) has to be inside the if($value !== '..' && $value!=='.')
3) What are you trying to achieve by the preg_match?
If you just want to match name completely, just do substr($value, 0, -4) == $name. Well this rely on extension having 3 characters, what's not perfect, but you rely on that already.