How can PHP developers ensure that uploaded files are stored in the correct directory on an FTP server and verify their existence before processing?

// Connect to FTP server
$ftp_server = "ftp.example.com";
$ftp_username = "username";
$ftp_password = "password";
$ftp_connection = ftp_connect($ftp_server);
$login = ftp_login($ftp_connection, $ftp_username, $ftp_password);

// Change to desired directory
$desired_directory = "/path/to/directory/";
ftp_chdir($ftp_connection, $desired_directory);

// Upload file
$local_file = "path/to/local/file.txt";
$remote_file = "file.txt";
ftp_put($ftp_connection, $remote_file, $local_file, FTP_BINARY);

// Verify file existence
$files = ftp_nlist($ftp_connection, ".");
if (in_array($remote_file, $files)) {
    echo "File uploaded successfully and exists in the directory.";
} else {
    echo "File upload failed or does not exist in the directory.";
}

// Close FTP connection
ftp_close($ftp_connection);