Reading Files

Delete questions are read.

To read specific parts of a file, one would use the blockread function

Gl
Mike

Or you should consider to use :
FileOpen, FileSeek, FileRead and FileClose.

Peter

hi all,

i would prefer to use a TFilestream
-with the position-property you can easy position the 'filecursor'
-with the method readbuffer you can easy copy a defined amount of bytes at position to the buffer

>Did you see the new look of ExpertExchange ? Why some rows are red ?
they are red, because the questioner has deleted the q, if another expert will pevent this, then the expert posts a comment on it and the q is live again, if no comment is added the q will disappear after a specific time.

meikl

listening..

try this:

procedure ReadFrom10To15(FileName: string; var Buf: array of Byte);
var
  F: File;
begin
  AssignFile(F, FileName);
  FileMode:= 0; // Read only
  Reset(F, 1);
  Seek(F, 10);
  BlockRead(F, Buf, 6);
  CloseFile(F);
end;

Comment:

This will read from byte 10 (11'th byte), because the first record is number 0, so that if you want to read from the 10'th byte you must change seek procedure to:

  Seek(F, 9);

Motaz

http://www.geocities.com/motaz1

hi,

seemed i have to give a sample too

procedure GetPartFromFile(FileName : String; FromPos, Size : Integer; var Buffer);
var F : TFileStream;
Begin
  try
    F := TFileStream.Create(FileName, fmOpenRead);
    try
      F.Position := FromPos;
      F.ReadBuffer(Buffer,Size);
    finally
      F.Free;
    end;
  except
    Raise;  //forward exception
  end;
end;

//how to call
procedure TForm1.Button1Click(Sender: TObject);
var MyBuf : Array[0..4] of Byte;
begin  //get bytes 11,12,13,14,15
  GetPartFromFile('c:\test.txt',10,SizeOf(MyBuf),MyBuf);
  showmessage(  //HexOutput
     Format('%x %x %x %x %x',[MyBuf[0],MyBuf[1],MyBuf[2],MyBuf[3],MyBuf[4]]));

end;

meikl

I suppose, while we are processing enumAllPossibleSolutions(exampleCallBackProc) :) one *could* also try this with memory mapped files :).



Gl
Mike

yup, thats missed ;-)

sample please