So istringstream copies the contents of a string when initialised, e.g

string moo("one two three four");
istringstream iss(moo.c_str());

I was wondering if there's a way to make std::istringstream use the given c_str as its buffer without copying things. This way, it won't have to copy large bits of memory before passing the std::istringstream& to functions that take istream& as an argument.

What I've been trying to do is convert some functions which only take std::ifstream& arguments (they're mostly parsers) into taking istream& as well. Would I have to make my own istream subclass for this?