搜索文件夹上已知扩展名的未知文件名

How to search on folder if a know the extension of files but dont know the filename.

presume i have a folder with files like this.

folder/1.txt
folder/2.txt
folder/3.txt

using this simple method i echo all the files wich filenames contains only numbers.

  for ($i=0; $i<=3; $i++) {
  $files = 'folder/'. $i .'.txt';

  echo "$i.txt <br />";;     

and the above code echo something like this

 1.txt
 2.txt
 3.txt

is possible to achieve if filenames contains letters? or even better letters and numbers.

aaa.txt
asdwe.txt
1asw2.txt

is this possible?

Do that with DirectoryIterator:

<?php

const DS = DIRECTORY_SEPARATOR;

$dir = new DirectoryIterator('your' . DS . 'direcory' . DS);

foreach ($dir as $fileinfo) {

  if (!$fileinfo->isDot()) {
    // relative url of file = $fileinfo->getPathname();
    // file name  = $fileinfo->getFilename();
    echo $fileinfo->getFilename() . '<br />';
  }

}