PHP | ftp_mdtm() Function

<?php
 
// Connect to FTP server
 
// Use a correct ftp server
$ftp_server = "localhost";
 
// Use correct ftp username
$ftp_username="user";
 
// Use correct ftp password corresponding
// to the ftp username
$ftp_userpass="user";

// File name or path to upload to ftp server
$file = "demo_test.txt";
 
// Establishing ftp connection 
$ftp_connection = ftp_connect($ftp_server) 
        or die("Could not connect to $ftp_server");

if($ftp_connection) {
    echo "successfully connected to the ftp server!";
    
    // Logging in to established connection with
    // ftp username password
    $login = ftp_login($ftp_connection, $ftp_username, $ftp_userpass);
    
    if($login) {
        
        // Checking whether logged in successfully or not
        echo "<br>logged in successfully!";
        
        // Storing last modified data in $last_mod
        $last_mod = ftp_mdtm($ftp_connection, $file);
        
        if ($last_mod != -1) {
            
            // Checking whether any error occurred or not 
            // while retrieving last modified data
            echo "<br> $file was modified on ". 
                    date("F d Y H:i:s.", $last_mod).".";
        }
        else {
            echo "<br>could not get last modified.";
        }
         
    }
    else {
        echo "<br>login failed!";
    }
        
    // Closing  connection
    if(ftp_close($ftp_connection)) {
        echo "<br>Connection closed Successfully!";
    } 
}
?>