The start and end of each year, month, week, and Day in Delphi

Startofayear ... Startoftheyear ... Endofayear ... Endoftheyear ... The start and end times of each year, month, week, day

{参数是指定的年、月、周、日}
DateUtils.StartOfAYear
DateUtils.StartOfAMonth
DateUtils.StartOfAWeek
DateUtils.StartOfADay

{参数是　TDateTime}
DateUtils.StartOfTheYear
DateUtils.StartOfTheMonth
DateUtils.StartOfTheWeek
DateUtils.StartOfTheDay

{参数是指定的年、月、周、日}
DateUtils.EndOfAYear
DateUtils.EndOfAMonth
DateUtils.EndOfAWeek　
DateUtils.EndOfADay

{参数是　TDateTime}
DateUtils.EndOfTheYear
DateUtils.EndOfTheMonth
DateUtils.EndOfTheWeek
DateUtils.EndOfTheDay

Unit Unit1;

Interface

Uses
Windows, Messages, sysutils, variants, Classes, Graphics, Controls, Forms,
Dialogs, Stdctrls;

Type
TForm1 = Class (Tform)
Procedure Formcreate (Sender:tobject);
End

Var
Form1:tform1;

Implementation

{$R *.DFM}

Uses dateutils;

Procedure Tform1.formcreate (Sender:tobject);
Var
Dt,t1,t2,t3,t4:tdatetime;
s1,s2,s3,s4:string;
Begin
DT: = Strtodatetime (' 2009-5-20 11:22:33 ');

T1: = Startofayear (2009);
T2: = startoftheyear (DT);
T3: = Endofayear (2009);
T4: = endoftheyear (DT);

S1: = FormatDateTime (' yyyy-m-d h:n:s:zzz ', T1); 2009-1-1 0:0:0:000
S2: = FormatDateTime (' yyyy-m-d h:n:s:zzz ', T2); 2009-1-1 0:0:0:000
S3: = FormatDateTime (' yyyy-m-d h:n:s:zzz ', T3); 2009-12-31 23:59:59:999
S4: = FormatDateTime (' yyyy-m-d h:n:s:zzz ', T4); 2009-12-31 23:59:59:999

T1: = Startofamonth (2009, 5); {May 2009}
T2: = startofthemonth (DT);
T3: = Endofamonth (2009, 5);
T4: = endofthemonth (DT);

S1: = FormatDateTime (' yyyy-m-d h:n:s:zzz ', T1); 2009-5-1 0:0:0:000
S2: = FormatDateTime (' yyyy-m-d h:n:s:zzz ', T2); 2009-5-1 0:0:0:000
S3: = FormatDateTime (' yyyy-m-d h:n:s:zzz ', T3); 2009-5-31 23:59:59:999
S4: = FormatDateTime (' yyyy-m-d h:n:s:zzz ', T4); 2009-5-31 23:59:59:999


T1: = Startofaweek (2009, 21); {2009 21st Week}
T2: = Startoftheweek (DT);
T3: = Endofaweek (2009, 21);
T4: = endoftheweek (DT);

S1: = FormatDateTime (' yyyy-m-d h:n:s:zzz ', T1); 2009-5-18 0:0:0:000
S2: = FormatDateTime (' yyyy-m-d h:n:s:zzz ', T2); 2009-5-18 0:0:0:000
S3: = FormatDateTime (' yyyy-m-d h:n:s:zzz ', T3); 2009-5-24 23:59:59:999
S4: = FormatDateTime (' yyyy-m-d h:n:s:zzz ', T4); 2009-5-24 23:59:59:999

T1: = Startofaday (2009, 140); {2009 140th Day}
T2: = startoftheday (DT);
T3: = Endofaday (2009, 140);
T4: = endoftheday (DT);

S1: = FormatDateTime (' yyyy-m-d h:n:s:zzz ', T1); 2009-5-20 0:0:0:000
S2: = FormatDateTime (' yyyy-m-d h:n:s:zzz ', T2); 2009-5-20 0:0:0:000
S3: = FormatDateTime (' yyyy-m-d h:n:s:zzz ', T3); 2009-5-20 23:59:59:999
S4: = FormatDateTime (' yyyy-m-d h:n:s:zzz ', T4); 2009-5-20 23:59:59:999
End

End.