学步园

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.