Re: [Dev-C++] student needs a little help

[Jason H. <jas...@bt...>]

MessageThe trick is to tailor your method of accessing the data to the =
type and quantity of data and the access speeds needed. In the store =
example a few thousand records wouldn't be unreasonable, and each record =
would be on average no more than 30 bytes each (roughly). Say you did =
have 10000 record at 50 bytes (adding space for list implementation =
etc...), that's 500,000 bytes, in other words just less than 500kb (say =
half a meg). On the scale of current memory usage that's pretty =
miniscule. There are cases where it's impracticle to use memory and you =
have to use disk stored systems, and there are a range of specialised =
algorithms for dealing with them, but on the whole most developers would =
just use a Database system for large scale data storage and retrieval. =
Another factor to account for is the fact that most OS's have a virtual =
memory ability, so in effect if you do load a large quantity of data =
into memory it will be be automaticaly placed into a disk storage =
system, and it saves you a lot of complex work on disk access =
algorithms.

Also by ordering a list of records into a predictable sequence you allow =
for the use of special searching algorithms, as aposed to the basic =
sequential search. What you use is yet again dependent upon scale and =
speed requirement. However there are whole volumes dedicated to this one =
subject alone so I won't go into detail here.

At a guess anything up to a couple of hundred megabytes is good for =
memory storage (dependent upon the OS and target system in use), and =
above that a more advanced data access system should be considered. Also =
of note is that memory has somewhere on a scale of 1000 times quicker =
access speeds than current disk technology.

After saying all that a linked list wouldn't be a perfect solution =
because it's not the fasted model, a tree would be more suited, but they =
all follow the same principal. Searching through 10000 records in a =
linked list in memory wouldn't take more than a few seconds either (at a =
guess).

Maybe you didn't want to know all that, but I think it's an interesting =
subject.

Jason.

----- Original Message -----=20
  From: Ioannis Vranos=20
  To: Dev-C++=20
  Sent: Saturday, February 16, 2002 4:22 PM
  Subject: RE: [Dev-C++] student needs a little help


  I am really with short programming experience (i have been programming =
since 2000) and i can't understand how we can use linked lists on a =
large scale program. E.g. imagine we have a datafile with 10000 records. =
We load all of them in memory in a linked list so as to sort them on the =
fly e.t.c.? In few words the question is how can we apply a linked list =
in many records?



  Ioannis

  * Ioannis Vranos
  * Programming pages: http://www.noicys.d2g.com
  * Alternative URL: http://run.to/noicys
    -----Original Message-----
    From: dev...@li... =
[mailto:dev...@li...] On Behalf Of Benjamin =
Wheeless
    Sent: Saturday, February 16, 2002 3:40 PM
    To: dev...@li...
    Subject: RE: [Dev-C++] student needs a little help


    In my opinion, what he uses is really up to him, whether that be a =
container, or forcing it through with brutish, inefficient code, or =
using your suggestion and sticking with the data file as his container.

    The only reason that I suggested linked lists is due to the fact =
that he (1) is a student and his professor probably gave him the =
assignment in hopes that he would figure out basic data structure =
techniques, while at the same time showing some initiative and =
creativity in solving the problem and (2) because a question was posed =
directly concerning linked lists and where to find more information on =
them.

    There is nothing "wrong" with any of these approaches that have been =
suggested.  It is really up to him and his comfort level and knowledge =
base that he currently has with the language.  Wouldn't you agree?

    Benjamin Wheeless
    Network Systems - Delta Airlines, Inc.
    Atlanta, GA - USA 30320