FileRead (Delphi)

Description

The following example uses a button, a string grid, and an Open dialog box on a form. When the button is clicked, you are prompted for a file name. When you click OK, the specified file is opened, read into a buffer, and closed. Then the buffer is displayed in two columns of the string grid. The first column contains the character values in the buffer. The second column contains the numeric values of the characters in the buffer.

Code

procedure TForm1.Button1Click(Sender: TObject);
var
  iFileHandle: Integer;
  iFileLength: Integer;
  iBytesRead: Integer;
  Buffer: PAnsiChar;
  i: Integer;
begin
  if OpenDialog1.Execute then
  begin
    try
      iFileHandle := SysUtils.FileOpen(OpenDialog1.FileName, fmOpenRead);
      iFileLength := SysUtils.FileSeek(iFileHandle,0,2);
      FileSeek(iFileHandle,0,0);
      Buffer := System.AllocMem(iFileLength + 1);
      iBytesRead := SysUtils.FileRead(iFileHandle, Buffer^, iFileLength);
      FileClose(iFileHandle);
      for i := 0 to iBytesRead-1 do
      begin
        StringGrid1.RowCount := StringGrid1.RowCount + 1;
        StringGrid1.Cells[1,i+1] := Buffer[i];
        StringGrid1.Cells[2,i+1] := IntToStr(Integer(Buffer[i]));
      end;
    finally
      FreeMem(Buffer);
    end;
  end;
end;

Uses

• System.SysUtils.FileOpen ( fr | de | ja )
• System.SysUtils.FileSeek ( fr | de | ja )
• System.SysUtils.FileRead ( fr | de | ja )
• System.AllocMem ( fr | de | ja )
• System.FreeMem ( fr | de | ja )