Go Premium for a chance to win a PS4. Enter to Win

x
?
Solved

saving arrays to dat

Posted on 2004-08-19
4
Medium Priority
?
276 Views
Last Modified: 2010-04-05
hey all :)
I need advice, I have been looking at several ways to save arrays of records to a file and I was wondering whats the best way.
I need to save several arrays of records ( static & dynamic), and the hard part is that dynamic arrays can have varying lengths,
and most of them will exceed 255 characters. Which means I cant use "file of TRecord" to save the records. And I want to
save all my array records (6-8 of them) to one file.

Now I have looked into TFileStream and writing the individual records out manually. And its ok, but tedious.
And TStringLists, which I can use... but how do I save them out in a non text format? I dont want users to be able to
read (or change) anything in the file. Anyway to change that?

thanx for your time...



0
Comment
Question by:LMuadDIb
4 Comments
 
LVL 34

Accepted Solution

by:
Slick812 earned 1000 total points
ID: 11849035
hello  LMuadDIb, , I have used the delphi TFileStream, many, many times to save all kinds of  data into a file, if you have an array of records, you can for loop through the array and write each record to the TFileStream, but you will need to store the "Length" of the array as a file data segment, so you can read the file later and know how many records to read out of it. . . , if you used NON-FIXED size variables  (like a  String) then you will need a diferent method to get in in and out of a file data segment, you would record the length of the string (usually an integer value) and then write all of the characters in the string to file. . . . I have made a web site for using the TfileStream for muti-segment data files at --

http://www.angelfire.com/hi5/delphizeus/customfiles.html
0
 
LVL 2

Assisted Solution

by:DarkCore_
DarkCore_ earned 200 total points
ID: 11849777
Or just you can try instead of saving in a bulk file, save into a XML file. Maybe more tedious ... but a solution at all.

Edu
0
 
LVL 3

Assisted Solution

by:lmikle
lmikle earned 200 total points
ID: 11853032
unit Unit2;

interface

uses Windows, SysUtils, Classes;

type
  TRec1 = record
    I : Integer;
    S : String;
  end;

  TRec2 = record
    I : Integer;
    B : Boolean;
  end;

procedure SaveToFile(FileName : String);
procedure LoadFromStream(FileName : String);

var
   Rec1 : Array [1..10] Of TRec1; // Static array
   Rec2 : Array of TRec2; // Dynamic array

implementation

procedure SaveToFile(FileName : String);
var
  I : Integer;
  FS : TFileStream;
  sSize : Integer;
  sData : String;
begin
  // Open file to write (create)
  FS := TFileStream.Create(FileName,fmCreate);

  // Save static array - we know numbers of items
  For I := 1 To 10 Do
    begin
      // Write integer
       FS.WriteBuffer(Rec1[I].I,SizeOf(Integer));

       // Write String - write length first, then write data
       sSize := Length(Rec1[I].S);
       sData := Rec1[I].S;
       FS.WriteBuffer(sSize,SizeOf(Integer));
       FS.WriteBuffer(sData[1],sSize);
    end;

  // Save dynamic array
  // Write number of items first
  sSize := Length(Rec2);
  FS.WriteBuffer(sSize,SizeOf(Integer));
  For I := Low(Rec2) To High(Rec2) Do
    begin
      FS.WriteBuffer(Rec2[I].I,SizeOf(Integer));
      FS.WriteBuffer(Rec2[I].B,SizeOf(Boolean));
    end;

  FS.Free;
end;

procedure LoadFromStream(FileName : String);
var
  I : Integer;
  FS : TFileStream;
  sSize : Integer;
  sData : String;
begin
  // Open file to read
  FS := TFileStream.Create(FileName,fmOpenRead);

  // read static array
  For I := 1 To 10 Do
    Begin
      // read integer
      FS.ReadBuffer(Rec1[I].I,SizeOf(Integer));

      // read string
      FS.ReadBuffer(sSize,SizeOf(Integer));
      SetLength(sData,sSize);
      FS.ReadBuffer(sData[1],sSize);
      Rec1[I].S := sData;
    End;

  // read dynamic array
  FS.ReadBuffer(sSize,SizeOf(Integer));
  SetLength(Rec2,sSize);
  For I := Low(Rec2) To High(Rec2) Do
    begin
      FS.ReadBuffer(Rec2[I].I,SizeOf(Integer));
      FS.ReadBuffer(Rec2[I].B,SizeOf(Boolean));
    end;

  FS.Free;
end;

end.
0
 
LVL 4

Author Comment

by:LMuadDIb
ID: 11877916
Slick812 thanx for that link :)
 DarkCore, I didnt even think about xml (which I have never used) but Im gonna check that out thanx
and  lmikle, thanx for the code
0

Featured Post

Free Tool: IP Lookup

Get more info about an IP address or domain name, such as organization, abuse contacts and geolocation.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Have you ever had your Delphi form/application just hanging while waiting for data to load? This is the article to read if you want to learn some things about adding threads for data loading in the background. First, I'll setup a general applica…
In my programming career I have only very rarely run into situations where operator overloading would be of any use in my work.  Normally those situations involved math with either overly large numbers (hundreds of thousands of digits or accuracy re…
This course is ideal for IT System Administrators working with VMware vSphere and its associated products in their company infrastructure. This course teaches you how to install and maintain this virtualization technology to store data, prevent vuln…
Want to learn how to record your desktop screen without having to use an outside camera. Click on this video and learn how to use the cool google extension called "Screencastify"! Step 1: Open a new google tab Step 2: Go to the left hand upper corn…

926 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question