LastOSError (C++)

Description

This code demonstrates the use of system error codes and how to transform them into C++ exceptions.

Code

void __fastcall TForm2::btRaiseLastClick(TObject *Sender)
{
        /* Set the last OS error to a bogus value. */
        System::SetLastError(ERROR_ACCESS_DENIED);
 
        try
        {
                RaiseLastOSError();
        }
        catch(EOSError* ex)
        {
                MessageDlg(String("Caught an OS error with code: ") +
                        IntToStr((int)ex->ErrorCode), mtError,
                        TMsgDlgButtons() << mbOK, 0);
        }
 
 
        /* Let the Delphi Exception dialog appear. */
        RaiseLastOSError(ERROR_NOT_ENOUGH_MEMORY);
 
        /* Finally, set the last error to none. */
        System::SetLastError(ERROR_SUCCESS);
 
        if (GetLastError() != ERROR_SUCCESS)
                MessageDlg(String("Whoops, something went wrong ") +
                  " in the mean time!", mtError, TMsgDlgButtons() << mbOK, 0);
 
        /* No exception should be thrown here. */
        RaiseLastOSError();
}

Uses

• System.SysUtils.RaiseLastOSError ( fr | de | ja )
• System.SetLastError ( fr | de | ja )
• System.GetLastError ( fr | de | ja )