Storing multiple inputs on the same buffer?

Say you need to store a persons First name and last Name. I know I could do so by:

    string firstname;
    string lastname;
    string fullname;

    cout << "Users firstname ? "; cin >> firstname;
    cout << "Users last name ? "; cin >> lastname;

    fullname = firstname + ' ' + lastname;

I would like to eliminate the two extra variables and the concatenation at the end.

I want to be able to continue input on a buffer before storing it in the variable.

Is there a way to do this?