Delphi中有没有计算两个日期之间天数的函数???

Question

title

Answer 1

对了，要先 Use DateUtils;

Answer 2

起用单元：DateUtils
function DaysBetween(const ANow,AThen:TDateTime):integer;
function dayspan(const ANow,AThen:TDateTime):Double;unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls,DateUtils;type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;implementation{$R *.dfm}procedure TForm1.Button1Click(Sender: TObject);
var
  i : Integer;
  f : Double;
begin
  //获取两个日期的天数
  i := DaysBetween(Now-500,Now);
  Showmessage(IntToStr(i)); //500
  //获取两个日期的天数
  f := DaySpan(Now-500,Now);
  Showmessage(FloatToStr(f)); //500
end;end.

Answer 3

var
   days:int;
 begin
    days:=trunc(date-strtodate('2002-1-1'));
  end;