gnu indian
hi, I am fairly new to boost and using it for serialization. Though I went through the archives, couldn't get a clear answer to the following:
How do I fseek in a file and load from an offset. I don't want to read the whole data in the file; which works ( as given in some tutorial); but normal fseekg and then loading apparently doesn't work. Here is the sample code:
Hi Mridul, the wanted behavior must be implemented outside of boost::serialization but is not complicated at all. The trick is to create multiple archives - everything that needs to be deserialized as one chunck needs to be serialized as one chunck. Roberts library is very symmetric in everything it does, as a quick rule. ;-) So if you modify your code slightly it will work:
const char* fileName = "xyz.txt";
// Create some objects const Obj o1(1, false); const Obj o2; const Obj o3(2, true); const Obj* const p1 = &o1; int p = 0; int q = 0;
// Save data { // Create an output archive std::fstream ofs(fileName);
{ boost::archive::binary_oarchive ar(ofs,boost::archive::no_header); // Write data ar & o1 & o2 & o3 & p1; } p = ofs.tellp(); { boost::archive::binary_oarchive ar(ofs,boost::archive::no_header); // Write data ar & o1 & o2 & o3 & p1; }
}
// Restore data Obj restored_o1; Obj restored_o2; Obj restored_o3; Obj* restored_p1; { // Create and input archive std::ifstream ifs(fileName); boost::archive::binary_iarchive ar(ifs, boost::archive::no_header ifs.seekg(p); ar & restored_o1 & restored_o2 & restored_o3 & restored_p1; }
Hope this helps, -- Christian Pfligersdorffer Software Engineering www.eos.info