Using a variable for #define

Question

Libcurl uses the following to define the email recipient:

#define RECIPIENT "<[email protected]>"

But what if I don't want to hard code the recipient? I want a user to be able to supply his/her own email address, so I need to find a way to do this:

std::string emailreceiver = "[email protected]";
#define RECIPIENT = emailreceiver

The recipient is used in this line:

rcpt_list = curl_slist_append(rcpt_list, RECIPIENT);

I'm assuming I can't simply change this to

std::string emailreceiver = "[email protected]";
rcpt_list = curl_slist_append(rcpt_list, emailreceiver);

Anyone have any suggestions?

Answer 1

Curl expects a C string (const char *), not a C++ string (std::string). So try:

std::string emailreceiver = "[email protected]";
rcpt_list = curl_slist_append(rcpt_list, emailreceiver.c_str());

There's no need to use a #define at all, that was just an example.

Answer 2

Your last snippet is probably pretty close. From the looks of things, curl is expecting a C-style string though, so you may have to change it to:

std::string emailreceiver = "[email protected]";
rcpt_list = curl_slist_append(rcpt_list, emailreceiver.c_str());