Hello! when compiled in debug mode, the following program causes an exception in the file p:\boost_1_33_0\include\boost-1_33\boost\iostreams\detail\ optional.hpp, line 54 (I'm using VC 7.1.3088, Windows XP): #include <iostream> #include // sink #include // stream using namespace std; class IOutput { public: virtual void print(int, const char*) const = 0; }; class Output : public IOutput { public: void print(int id, const char* a) const { cout << a; } }; static IOutput* gpOutput; template<int id> class my_sink : public boost::iostreams::sink { public: std::streamsize write(const char* s, std::streamsize n) { gpOutput->print(id, s); std::streamsize sz = 0; for( const char* p=s; *p; ++p ) sz++; return sz; } }; typedef boost::iostreams::stream > output; int main() { gpOutput = new Output; output stream; stream << "Daniel" << endl; return 0; } When I compile in release mode the program prints `Daniel', just as expected. Is there a problem with my program? Thanks in advance! Hälsningar, Daniel