unit Unit1; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls; type TForm1 = class(TForm) Button1: TButton; procedure Button1Click(Sender: TObject); end; var Form1: TForm1; implementation {$R *.dfm} procedure TForm1.Button1Click(Sender: TObject); var x,y: Real; begin x := Frac(456.123); y := Frac(-456.123); ShowMessage(FloatToStr(x)); {返回:0.123} ShowMessage(FloatToStr(y)); {返回:-0.123} end; end.