I apologize, if i have missed something. Reading the documentation about boost::iostreams library I could not find the information which return type the boost::iostreams::stream's class is giving me calling read(). I searched through the headers and every read() found returns std::streamsize, which sounds reasonable to me. I was surprised, that the code below does not compile --------start code ---------- #include <boost/iostreams/stream.hpp> #include <boost/iostreams/device/file.hpp> int main(void){ boost::iostreams::stream<boost::iostreams::file_source> istr(std::string("in.pdf")); char *buffer = new char[10]; std::streamsize i = istr.read(buffer,10); return 0; } -------end code----------- and gives me: test.cpp:7: error: invalid conversion from ‘void*’ to ‘std::streamsize’ Could someone shed a light on me, please? Thanks in advance. kind regards Axel