Convert txt,docx,doc,to pdf using Php

Question

I have to make a script in PHP where it will read several files and turn them all into PDF. I’m using the FPDF but I’m having difficulties in the logic of making it read each file in my directory and turn it into PDF. Someone can give me a light?

<?php
//require('gerapdf.php');

 $pasta = 'C:\xampp\www\listar\pdf';
 $listar  = new RecursiveDirectoryIterator($pasta);
 $recursivo = new RecursiveIteratorIterator($listar);


 foreach($recursivo as $obj){
     echo '<a href="'.$obj->getPathname().'">'.$obj->getFilename().'</a><br/>';

 }