Question

我正在尝试在 delphi 5 中的给定范围内生成随机的Tdatetime值 让我们说两个日期都遵循以下格式

date1=01/01/2018 12:35:32 date2=05/01/2018 21:35:32

我要生成一个在此范围之间增加的“ x”日期。例如，我想从date1-> date2
范围生成7个日期
randomdate[0]:=01/01/2018 12:35:32 randomdate[1]:=01/01/2018 14:35:12 randomdate[2]:=01/01/2018 16:42:22 randomdate[3]:=02/01/2018 21:12:01 randomdate[4]:=03/01/2018 11:13:12 randomdate[5]:=04/01/2018 22:20:05 randomdate[6]:=05/01/2018 20:30:05

问题在于，如果第二个随机日期充实了date2，则所有其他日期必须与date2相同，但是如果时间达到23:59:59，则下一个日期将超出范围

就像下面的小报

randomdate[0]:=01/01/2018 12:35:32 randomdate[1]:=05/01/2018 23:59:59 .................................

！从现在开始的所有日期都是

06/01/2018 23:59:59

这超出了我的范围！

任何帮助将不胜感激

在Andreas建议之后，这里是在D5上工作的最终代码，所以我猜想在所有其他版本的delphi上工作

unit Unit1; interface uses Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls, ComCtrls; type TForm1 = class(TForm) RichEdit1: TRichEdit; Edit1: TEdit; Edit2: TEdit; Button1: TButton; Edit3: TEdit; Label1: TLabel; Label2: TLabel; Label3: TLabel; procedure Button1Click(Sender: TObject); procedure FormCreate(Sender: TObject); private { Private declarations } public { Public declarations } end; var Form1: TForm1; implementation {$R *.DFM} function SecondsBetween(const Time1, Time2: TDateTime): Longint; const SecsPerMin=60; const MinsPerHour=60; const HoursPerDay=24; begin result := Round(SecsPerMin * MinsPerHour * HoursPerDay * Abs(Time2 - Time1)); end; function RandomDateTime( AFrom, ATo: TDateTime): TDateTime; var SecsBetween: int64; begin SecsBetween := SecondsBetween(AFrom,ATo); result := AFrom + (Round(SecsBetween * Random) / (60*60*24)); end; function CreateSortedListOfRandomDatetimes( AFrom, ATo: TDateTime; N: integer): TStringlist; var i: Integer; begin result := Tstringlist.Create; try // result.Capacity := N; // for an unnoticeable increase in performance for i := 1 to N do result.Add(formatdatetime('dd/mm/yyyy hh:nn:ss',RandomDateTime(AFrom, ATo))); result.Sort; except result.Free; raise; end; end; //edit1 Holds the 1st date which is 04/09/2018 16:00:00 //edit2 hold the 2nd date //edit3 holds the N count value procedure TForm1.Button1Click(Sender: TObject); var timestamps: Tstringlist; i: Integer; d1:Tdatetime; d2:Tdatetime; begin d1:=StrtoDatetime(edit1.text); d2:=StrtoDatetime(edit2.text); timestamps := CreateSortedListOfRandomDatetimes(d1,d2 ,strtoInt(edit3.text)); try RichEdit1.Lines.BeginUpdate; try RichEdit1.Lines.Clear; for i := 0 to timestamps.Count - 1 do RichEdit1.Lines.Add(timestamps.strings[i]) finally RichEdit1.Lines.EndUpdate; end; finally timestamps.Free; end; end; procedure TForm1.FormCreate(Sender: TObject); begin randomize; end; end.

Answer 1

可以像这样（TDateTime）编写在两个固定值之间生成随机uses DateUtils值的函数：

function RandomDateTime(const AFrom, ATo: TDateTime): TDateTime;
var
  SecsBetween: Int64;
begin
  SecsBetween := SecondsBetween(AFrom, ATo);
  result := IncSecond(AFrom, Round(SecsBetween * Random));
end;

要创建这些的排序列表，请使用您喜欢的排序方法。在现代的Delphi中，您可以使用内置的通用列表：

function CreateSortedListOfRandomDatetimes(const AFrom, ATo: TDateTime; N: integer): TList<TDateTime>;
var
  i: Integer;
begin
  result := TList<TDateTime>.Create;
  try
    result.Capacity := N; // for an unnoticeable increase in performance
    for i := 1 to N do
      result.Add(RandomDateTime(AFrom, ATo));
    result.Sort;
  except
    result.Free;
    raise;
  end;
end;

尝试一下：

procedure TForm1.FormCreate(Sender: TObject);
var
  timestamps: TList<TDateTime>;
  i: Integer;
begin
  timestamps := CreateSortedListOfRandomDatetimes(
    EncodeDateTime(2000, 1, 1, 0, 0, 0, 0),
    EncodeDateTime(2000, 12, 31, 23, 59, 59, 999),
    10
  );
  try
    RichEdit1.Lines.BeginUpdate;
    try
      RichEdit1.Lines.Clear;
      for i := 0 to timestamps.Count - 1 do
        RichEdit1.Lines.Add(DateTimeToStr(timestamps[i]))
    finally
      RichEdit1.Lines.EndUpdate;
    end;
  finally
    timestamps.Free;
  end;
end;

（此方法可能会产生重复的日期时间。Q并未明确提及是否允许这样做。而且，它仅以第二精度而不是毫秒精度工作。您可能要更改它，或至少删除AFrom的毫秒数。）

Delphi生成日期时间范围之间的随机日期时间值

1 个答案: