Thread: Adapting this function

What is the reason for using a list container instead of, say, a vector?

Kuphryn

It's a legacy application running on an ancient dos machine. Can't really start messing around with the whole structure.

A list container is no efficient for random access. One solution is iterator.

// Traverse to tenth element from the end of list container
std::const_iterator iRandom = listData.end() - 10;

Kuphryn

Just want to get this clear. I can use this with my current program, something like...

Code:

ifstream is(fname.c_str(), ios::binary);//open binary input file
std::const_iterator iRandom = lst.end() - 10; // set position
   //while we can read a book from the file
   while (is.read(reinterpret_cast<char *>(&bo), sizeof(bookobject)))
   {
      bookwithposition bwp(bo);  //make book with position
      bwp.setPosition(index++);  //set position
   lst.insert(bwp);           //add to list
   }
   is.close();//close file when we have done

Think I have something that's almost there but when I call it it doesn't seem to output any of the list items.

Code:

void dolatest(string fname, BuckDoubleLinkedList<bookwithposition>& lst)
{
	int index = 0; // declare and initialise index
   bookobject bo;

   ifstream is(fname.c_str(), ios::binary);//open binary input file
   int count = 0; // cout used to discover the number of book entries
   while (is.read(reinterpret_cast<char *>(&bo), sizeof(bookobject)))
   {
   	bookwithposition bwp(bo); // make book with position
      bwp.setPosition(count++); // set position
   }
   index = count - 5; // set the position to the last five entries
   cout << index << endl;
   //while we can read a book from the file
   while (is.read(reinterpret_cast<char *>(&bo), sizeof(bookobject)))
   {
      bookwithposition bwp(bo);  //make book with position
      bwp.setPosition(index++);  //set position
   	lst.insert(bwp);           //add to list
   }
   is.close();//close file when we have done
   cout << endl;
}

This is called by...

Code:

void latest(string fname)
{
   BuckDoubleLinkedList<bookwithposition> list('a');
   dolatest(fname, list); // call function to produce a list
   list.printList(); // display the list
   system("pause");
}

the dolatest function is adapted from a function which outputs all of the items which works fine. Any help appreciated.