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"Invald Pointer Operation" on Setlength of dynamic array

Posted on 2014-11-11
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Medium Priority
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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;

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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
2 Comments
 
LVL 19

Accepted Solution

by:
MerijnB earned 2000 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;
                                  

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0
 

Author Closing Comment

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

Cheers
    Shawn
0

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