Solved

"Invald Pointer Operation" on Setlength of dynamic array

Posted on 2014-11-11
2
262 Views
Last Modified: 2014-11-12
Hi guys, I have a very simple program (I'm trying to do a little speed comparison between StrCopy, StrMove, and Move), and I keep getting an Invalid Pointer Operation on the 2nd time through my "while" loop on this line:

SetLength(HOutBuffer2, hlength);

Here's my code:

var
  Form1: TForm1;
  infiletext : TGpTextFile;
  outfilestream : TGpHugeFileStream;
  inrec : string;
  bytes_Wrote, hlength : integer;
  HOutbuffer2 : array of Char;

implementation

{$R *.dfm}


procedure TForm1.Button1Click(Sender: TObject);
begin
  infiletext:=TGpTextFile.CreateEx('bigtest.txt', FILE_ATTRIBUTE_NORMAL, GENERIC_READ);
  infiletext.Reset();
  outfilestream:=TGpHugeFileStream.Create('outstream.txt', accWrite);


  while not infiletext.EOF do
  begin
    inrec:=infiletext.Readln;
    hlength := length(inrec)+2;

    SetLength(HOutBuffer2, hlength);
    StrCopy(PChar(HOutBuffer2), PChar(inrec+#13#10));

    bytes_Wrote:=OutFileStream.Write(HoutBuffer2[0], hlength);
  end; // WHILE

  infiletext.Close;
  infiletext.Free;
  OutFileStream.Free;
end;

Open in new window


It does the 1st iteration of the loop fine, then crashes 2nd time through on "SetLength(HOutBuffer2, hlength);"

Thanks!
   Shawn
0
Comment
Question by:shawn857
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
2 Comments
 
LVL 19

Accepted Solution

by:
MerijnB earned 500 total points
ID: 40436783
I guestimate the problem lies in the StrCopy, where you cast the dynamic array to PChar.
Change it to a CopyMemory(), the exact code depends on whether these are ansi or unicode chars and strings (which Delphi version are you using?)

This will probably work:

var
  Form1: TForm1;
  infiletext : TGpTextFile;
  outfilestream : TGpHugeFileStream;
  inrec : string;
  bytes_Wrote, hlength : integer;
  HOutbuffer2 : array of Char;

implementation

{$R *.dfm}


procedure TForm1.Button1Click(Sender: TObject);
begin
  infiletext:=TGpTextFile.CreateEx('bigtest.txt', FILE_ATTRIBUTE_NORMAL, GENERIC_READ);
  infiletext.Reset();
  outfilestream:=TGpHugeFileStream.Create('outstream.txt', accWrite);


  while not infiletext.EOF do
  begin
    inrec:=infiletext.Readln + #13#10;
    hlength := length(inrec);

    SetLength(HOutBuffer2, hlength);
    CopyMemory(@HOutBuffer2[0], @inrec[1], hlength*sizeof(char));

    bytes_Wrote:=OutFileStream.Write(HoutBuffer2[0], hlength);
  end; // WHILE

  infiletext.Close;
  infiletext.Free;
  OutFileStream.Free;
end;
                                  

Open in new window

0
 

Author Closing Comment

by:shawn857
ID: 40438740
Thanks Merijn, that did the trick!

Cheers
    Shawn
0

Featured Post

Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

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

This article explains how to create forms/units independent of other forms/units object names in a delphi project. Have you ever created a form for user input in a Delphi project and then had the need to have that same form in a other Delphi proj…
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…
This video shows how to use Hyena, from SystemTools Software, to update 100 user accounts from an external text file. View in 1080p for best video quality.

740 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