Solved

Put "bytes" in a Unicode string declared variable in Delphi 2009

Posted on 2009-05-20
4
615 Views
Last Modified: 2013-11-23
I am converting an application from Turbo Delphi 2006 to Delphi 2009
Somewhere, I use a "generic" function that receives an array of string in input plus additional database information, and puts these data into some SQL table
Up to now (Turbo Delphi 2006), no problem, even for those strings that in fact contain binary data to be stored in blob fields in the database
But now come Delphi 2009 where all strings are unicode.
I need to keep using that generic function, as well as the "array of unicodestring" mechanism, but I wonder how the calling program can put a string containing bytes (declared as ansistring and filled in with the content of an external binary file for example)  in a unicodestring without those bytes being converted, one way of another
Thanks
0
Comment
Question by:LeTay
  • 3
4 Comments
 
LVL 12

Accepted Solution

by:
Hypo earned 500 total points
ID: 24431745
Hi,
I don't know if this is what you are looking for, or if there are som native way of doing this, but this example shows one way of putting data into a unicode string by moving the memory into and out of the string. See the example below.

/Hypo
unit Unit1;
 

interface
 

uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, ComCtrls, StrUtils, StdCtrls, ExtCtrls;
 

type

  TForm1 = class(TForm)

    Memo1: TMemo;

    Button1: TButton;

    Button2: TButton;

    procedure FormCreate(Sender: TObject);

    procedure Button1Click(Sender: TObject);

    procedure Button2Click(Sender: TObject);

  private

    { Private declarations }

  public

    { Public declarations }

    FData : Array[0..1000] of Byte;

    FDataPos : Integer;

  end;
 

var

  Form1: TForm1;
 

implementation
 

{$R *.dfm}
 

// Returns the index in the string where the data was inserted...

Function AddBytesToUnicodeString(var Data; Count : Integer; var AText : String) : Integer;

Begin

  Result := Length(AText)+1;

  SetLength(AText, Result+((Count+1) shr 2));

  Move(Data, AText[Result], Count);

End;
 

Procedure GetBytesFromUnicodeString(AText : String; Index : Integer; var Data; Count : Integer);

Begin

  Move(AText[Index], Data, Count);

End;
 

procedure TForm1.FormCreate(Sender: TObject);

var i : Integer;

begin

  // Create a block of random data...

  Randomize;

  for i := 0 to Length(FData)-1 do

    FData[i] := Random(255);

end;
 

// Move FData into Memo1.Text

procedure TForm1.Button1Click(Sender: TObject);

var AText : string;

begin

  AText := Memo1.Text;

  FDataPos := AddBytesToUnicodeString(FData[0], Length(FData), AText);

  Memo1.Text := AText;

end;
 

// Get the Data from the memo into ReadData block

procedure TForm1.Button2Click(Sender: TObject);

var i : Integer;

    ReadData : Array of Byte;

begin

  SetLength(ReadData, Length(FData));

  try

    GetBytesFromUnicodeString(Memo1.Text, FDataPos, ReadData[0], Length(FData));

    // Verify the data we read against the source... 

    for i := 0 to Length(ReadData)-1 do

      if ReadData[i] <> FData[i] then

        raise Exception.Create('Data is not similar: '+IntToStr(i));

    ShowMessage('Data read and restored successfully.');

  finally

    ReadData := nil; 

  end;

end;
 

end.

Open in new window

0
 

Author Comment

by:LeTay
ID: 24431795
Hello Hypo !
You again !
This is nice.
In fact, the "buffer" is initally a ANSIString variable that has been filled in via another function which copy integrally the content of a (binary) file into it
I will look at the code you propose
Thanks !
ps : there may be some delay as I may not come back on this issue very often in the coming weeks
0
 

Author Comment

by:LeTay
ID: 24913747
Hello Hypo
I looked at your code that works fine
I want now to change it a little bit, see code attached
But it does not work
At least I know that in the second procedure, Data needs to be "initialised". I mean, needs the equivalent of SetLength to be performed first, but what should I do to achieve that ?
My final goal is finally to have these procedures in place
=> MoveANSI2UnicodeString
=> MoveUnicodeString2Bytes
Thanks
procedure MoveBytes2UnicodeString(var Data;Length:integer;var UNI:UnicodeString);

begin

 SetLength(UNI,1 + ((Length + 1) shr 2));

 Move(Data,UNI[1],Length);

end;
 

procedure MoveUnicodeString2Bytes(UNI:UnicodeString;var Data);

begin

 Move(UNI[1],Data,Length(UNI) * 2);

end;

Open in new window

0
 

Author Comment

by:LeTay
ID: 24913862
Hello Hypo,
I am here again
The final code I want to use is attached but it fails
I don't understand why
Can you help ?
Thanks
procedure MoveANSI2UnicodeString(var ANSI:ANSIString;UNI:UnicodeString);

begin

 SetLength(UNI,1 + ((Length(ANSI) + 1) shr 2));

 Move(ANSI,UNI[1],Length(ANSI));

end;
 

procedure MoveUnicodeString2ANSI(var UNI:UnicodeString;ANSI:ANSIString);

begin

 SetLength(ANSI,Length(UNI) * 2);

 Move(UNI[1],ANSI,Length(UNI) * 2);

end;

Open in new window

0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

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

Suggested Solutions

In this tutorial I will show you how to use the Windows Speech API in Delphi. I will only cover basic functions such as text to speech and controlling the speed of the speech. SAPI Installation First you need to install the SAPI type library, th…
Introduction Raise your hands if you were as upset with FireMonkey as I was when I discovered that there was no TListview.  I use TListView in almost all of my applications I've written, and I was not going to compromise by resorting to TStringGrid…
The viewer will learn how to use NetBeans IDE 8.0 for Windows to connect to a MySQL database. Open Services Panel: Create a new connection using New Connection Wizard: Create a test database called eetutorial: Create a new test tabel called ee…
The viewer will learn how to use and create keystrokes in Netbeans IDE 8.0 for Windows.

930 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

Need Help in Real-Time?

Connect with top rated Experts

8 Experts available now in Live!

Get 1:1 Help Now