SystemIOResult (Delphi)

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Description

This example illustrates how to use IOResult to check the success of the Reset method. If the call to Reset is successful, a message dialog displays the size of the file that you select in an Open dialog. If the call to Reset fails, a message warns you that there was a file access error. To test the failure part of this example, just misspell a file name in the open dialog.

Code

procedure TForm1.Button1Click(Sender: TObject);
var
  F: File of Byte;
begin
  if OpenDialog1.Execute then
  begin
    AssignFile(F, OpenDialog1.FileName);
    {$I-}
    Reset(F);
    {$I+}
    if IOResult = 0 then
    begin
      MessageDlg('File size in bytes: ' + IntToStr(FileSize(F)),
        mtInformation, [mbOk], 0);
      CloseFile(F);
    end
    else
      MessageDlg('File access error', mtWarning, [mbOk], 0);
  end;
end;

Uses

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