Compilare: user.cpp: In function ‘int main()’: user.cpp:166:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int j = 0; j < list[i].size(); j ++ ) ^ user.cpp: In member function ‘void input_reader::advance()’: user.cpp:25:49: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread( buffer, SIZE, 1, input_file ); ^ user.cpp: In constructor ‘input_reader::input_reader(const char*)’: user.cpp:35:45: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread( buffer, SIZE, 1, input_file ); ^