procedure TForm1.Button1Click(Sender: TObject);
var
B: Byte;
I: LongWord;
begin
//测试一:长数据类型向短数据类型转换,高位字节舍去
I := $000000FF;
B := Byte(I);
if B = $FF then Showmessage('OK');
//如果把I的高位的三个字节的$000000换成任意数字,转换后都是$FF
//测试二:短数据类型向长数据类型转换,高位填0
B := $FF;
I := LongWord(B);
Showmessage(Format('%.8x', [I]));
end;