This ostream base64-encodes all data written to it and forwards it to a connected ostream. Always call close() when done writing data, to ensure proper completion of the encoding operation.

The class implements RFC 4648 - https://tools.ietf.org/html/rfc4648

Note: The characters are directly written to the ostream's streambuf, thus bypassing the ostream. The ostream's state is therefore not updated to match the buffer's state.