Hi there I just have a simple question regarding the format of a zlib archive. Somehow WinRar cannot read the archive. If I use the simple example application provided in the zlib distribution WinRar is able to read it. This makes me wondering what difference is in the archive generated by boost::iostreams? Here is my example code which works fine. I using VC7.1 and Boost 1.33 #include <iostream> #define BOOST_IOSTREAMS_NO_LIB #include <boost/iostreams/device/file.hpp> #include <boost/iostreams/filtering_stream.hpp> #include <boost/iostreams/filter/zlib.hpp> namespace io = boost::iostreams; int _tmain(int argc, _TCHAR* argv[]) { { io::filtering_ostream out; out.push( io::zlib_compressor() ); out.push( io::file_sink( "hello.zip" )); out << "Hello boost::iostreams"; //close the file } io::filtering_istream in; in.push( io::zlib_decompressor() ); in.push( io::file_source( "hello.zip" )); std::string strMessage; std::getline( in, strMessage ); std::cout << strMessage << std::endl; return 0; } Besides the problem, seems that boost::iostream is an amazing lib and a huge contribution for the C++ community. Thanks, Christian