How do I determine (using c++ and winsock) the site protocol based on the URL, for example (www.google.com) if the protocol is not known in advance?
Or how do I determine web server TCP port?
I want do an HTTP get request using the link which after www. and need to determine the port or protocol, in order to use http over tls or simple http.
You can't. You decide the protocol you're going to use to contact some server. If you haven't decided it, you don't know it. Certainly your computer can't tell you what it will be.
It's like asking a supermarket cashier what you're going to buy today. They don't know that. You are supposed to tell them that.
What you can do is to see whether a website on that server automatically redirects HTTP traffic to a HTTPS URI (thus enforcing SSL), or otherwise blocks non-HTTPS traffic. If that's what you want to do, you can achieve it by attempting to make an HTTP connection to that domain and see what happens.
Depending on your web browser make/model/version, that may be what it is doing when you enter "www.google.com" without specifying a protocol: assuming http:// then following any remote redirects that take you to https:// instead. Pretty soon, though, or already if you have certain extensions installed, the default is going to be https://. I must stress though, again, that this is still the client (i.e. the browser) making the decision, not the server; if you are writing your own browser then, again, you must choose what that default should be.