What are the key differences between using copy() and ftp_put() functions for file transfer in PHP?

The key difference between using the copy() and ftp_put() functions for file transfer in PHP is the method of transfer. The copy() function is used for transferring files within the same server or between servers that are directly accessible, while the ftp_put() function is used for transferring files to a remote server via FTP. If you need to transfer files between servers that are not directly accessible, you should use the ftp_put() function.

// Using ftp_put() function to transfer a file to a remote server via FTP
$ftp_server = 'ftp.example.com';
$ftp_username = 'username';
$ftp_password = 'password';
$local_file = 'local_file.txt';
$remote_file = 'remote_file.txt';

$ftp_conn = ftp_connect($ftp_server);
ftp_login($ftp_conn, $ftp_username, $ftp_password);
ftp_put($ftp_conn, $remote_file, $local_file, FTP_ASCII);
ftp_close($ftp_conn);