Hello I've been trying to get boost iostreams filter to work. Heres the code I managed to write, but theres something I cannot understand.. It works fine with one small text file and it will process the lines okay, but when I try to use another text file (which is much bigger) it wont recognize any line and will return 0 lines counted (though file has around 2 million lines).. What am I doing wrong? What could be the cause of this? Best regards Thanks for help Heres the code: #include <boost/iostreams/device/file.hpp> #include <boost/iostreams/filtering_stream.hpp> #include <boost/iostreams/filter/newline.hpp> #include <boost/iostreams/filter/line.hpp> #include <boost/ref.hpp> #include <fstream> #include <ostream> #include <iostream> #include <string> using namespace std; using namespace boost::iostreams; namespace io = boost::iostreams; class long_line_counter : public io::line_filter { public: explicit long_line_counter(int max_length = 80) : max_(max_length), count_(0) { } int count() const { return count_; } private: std::string do_filter(const std::string& line) { ++count_; return line; } int max_; int count_; }; int main() { filtering_istream fin; long_line_counter llc(80); fin.push(boost::ref(llc)); fin.push(file_source("test2.txt", ios::in | ios::binary)); char buf[4012]; while ( fin.read(buf, 4012) && (llc.count() < 7000) ) { std::cout << "read" << "\n"; } std::cout << llc.count() << "\n"; return 0; }