Yep. stringstreams make copies of passed strings too. I had to hack around that once like this: struct ZeroCopyBuf : public std::streambuf { ZeroCopyBuf

Yep. stringstreams make copies of passed strings too. I had to hack around that once like this: struct ZeroCopyBuf : public std::streambuf { ZeroCopyBuf(const std::string &s) : ZeroCopyBuf(s.c_str(), s.length()) {} ZeroCopyBuf(const char *c, std::size_t l) : ZeroCopyBuf(const_cast<char*>(c), l) {} ZeroCopyBuf(char *c, std::size_t l) { setg(c, c, c + l); } }; ... std::string s ...; ZeroCopyBuf buf(s); std::istream is(&buf); Terrible. C++-20 makes it better by adding move semantics to most methods... Still.