只读pdf文件并在目录中获取该pdf文件的文件名

I need to read only pdf files in a directory and then read the filename of every files then I will use the filename to rename some txt files. I have tried using only eregi function. but it seems cannot read all I need. how to read them well? here's my code :

$savePath   ='D:/dir/';
$dir       = opendir($savePath);
$filename  = array();

while ($filename = readdir($dir)) {
if (eregi("\.pdf",$filename)){
    $read = strtok ($filename,"."); //get the filenames

//to rename some txt files using the filenames that I get before
//$testfile is text files that I've read before
    $testfile = "$read.txt";
    $file = fopen($testfile,"r") or die ('cannot open file');

    if (filesize($testfile)==0){} 
    else{
        $text = fread($file,55024);
        fclose($file);
        echo "</br>"; echo "</br>";         
    }
}

More elegant:

foreach (glob("D:/dir/*.pdf") as $filename) {
    // do something with $filename
}

To get the filename only:

foreach (glob("D:/dir/*.pdf") as $filename) {
    $filename = basename($filename);
    // do something with $filename
}

You can do this by filter file type.. following is sample code.

<?php 

// directory path can be either absolute or relative 
$dirPath = '.'; 

// open the specified directory and check if it's opened successfully 
if ($handle = opendir($dirPath)) { 

   // keep reading the directory entries 'til the end 
   $i=0; 
   while (false !== ($file = readdir($handle))) { 
   $i++; 

      // just skip the reference to current and parent directory 
      if (eregi("\.jpg",$file) || eregi("\.gif",$file) || eregi("\.png",$file)){ 
         if (is_dir("$dirPath/$file")) { 
            // found a directory, do something with it? 
            echo " [$file]<br>"; 
         } else { 
            // found an ordinary file 
            echo $i."- $file<br>"; 
         } 
      } 
   } 

   // ALWAYS remember to close what you opened 
   closedir($handle); 
}  

?>

Above is demonstrating for file type related to images you can do the same for .PDF files.

Better explained here