目录
Delphi10时间、计时相关方法之 -软件的基本是要处理好”算法“及其基础（四）
2.6.2、日期时间格式化记录（结构体）TFormatSettings的格式化字符串Format：
Delphi10时间、计时相关方法之 -软件的基本是要处理好”算法“及其基础（四）
一、计时
1.1、粗犷计时类TTimer
uses FMX.Types; //: for FMX
uses Vcl.ExtCtrls; //: for VCL
1.2、精确计时类TStopwatch
uses System.Diagnostics;
1.3、时间跨度类TTimeSpan
uses System.TimeSpan;
二、时间
2.1、TDateTime
TDateTime = type Double;
PDateTime = ^TDateTime;
TDate = type TDateTime;
TTime = type TDateTime;
uses System ;
2.2、DateTimeToOleAutoString
function DateTimeToOleAutoString(const DateTime: TDateTime): string; inline;
uses System.VarUtils; //: Variant Utilities Unit
2.3、VarToDateTime
function VarToDateTime(const V: Variant): TDateTime;
uses System.Variants;
2.4、VarFromDateTime
function VarFromDateTime(const DateTime: TDateTime): Variant;
uses System.Variants;
2.5、DateTimeToWinFileDate
function DateTimeToWinFileDate(DateTime: TDateTime): UInt32;
function WinFileDateToDateTime(FileDate: UInt32; out DateTime: TDateTime): Boolean;
uses System.Zip;
2.6、系统工具单元SysUtils中相关日期时间
2.6.1、方法（函数、过程）
{ Date and time record 天、时间的记录}
TTimeStamp = record
Time: Integer; { Number of milliseconds since midnight }
Date: Integer; { One plus number of days since 1/1/0001 }
end;
uses System.SysUtils;
{ Date encoding and decoding日期编解码 }
function EncodeDate(Year, Month, Day: Word): TDateTime;
function TryEncodeDate(Year, Month, Day: Word; out Date: TDateTime): Boolean;
procedure DecodeDate(const DateTime: TDateTime; var Year, Month, Day: Word);
function DecodeDateFully(const DateTime: TDateTime; var Year, Month, Day, DOW: Word): Boolean; //:含闰年处理
function DateTimeToTimeStamp(DateTime: TDateTime): TTimeStamp;
function TimeStampToDateTime(const TimeStamp: TTimeStamp): TDateTime;
{ Time encoding and decoding时间编解码 }
function EncodeTime(Hour, Min, Sec, MSec: Word): TDateTime;
function TryEncodeTime(Hour, Min, Sec, MSec: Word; out Time: TDateTime): Boolean;
function TimeStampToMSecs(const TimeStamp: TTimeStamp): Comp; // : Comp : uses System ; // : 时间截转毫秒数
function MSecsToTimeStamp(MSecs: Comp): TTimeStamp; // : Comp : uses System ; // : 毫秒数转时间截
procedure DecodeTime(const DateTime: TDateTime; var Hour, Min, Sec, MSec: Word);
{$IFDEF MSWINDOWS}
procedure DateTimeToSystemTime(const DateTime: TDateTime; var SystemTime: TSystemTime);
function SystemTimeToDateTime(const SystemTime: TSystemTime): TDateTime;
function TrySystemTimeToDateTime(const SystemTime: TSystemTime; out DateTime: TDateTime): Boolean;
{$ENDIF MSWINDOW}
function DayOfWeek(const DateTime: TDateTime): Word;
function Date: TDateTime;
function Time:TDateTime;
function Now: TDateTime; //: corresponding to 当前Date + Time
function CurrentYear: Word; //: corresponding to 当前时间Now的年份
function IncMonth(const DateTime: TDateTime; NumberOfMonths: Integer = 1): TDateTime;
procedure IncAMonth(var Year, Month, Day: Word; NumberOfMonths: Integer = 1);
procedure ReplaceTime(var DateTime: TDateTime; const NewTime: TDateTime);
procedure ReplaceDate(var DateTime: TDateTime; const NewDate: TDateTime);
function IsLeapYear(Year: Word): Boolean; //:某年是否闰年
function DateToStr(const DateTime: TDateTime): string; overload; inline;
function DateToStr(const DateTime: TDateTime; const AFormatSettings: TFormatSettings): string; overload; inline;
function TimeToStr(const DateTime: TDateTime): string; overload; inline;
function TimeToStr(const DateTime: TDateTime; const AFormatSettings: TFormatSettings): string; overload; inline;
function DateTimeToStr(const DateTime: TDateTime): string; overload; inline;
function DateTimeToStr(const DateTime: TDateTime; const AFormatSettings: TFormatSettings): string; overload; inline;
function StrToDate(const S: string): TDateTime; overload; inline;
function StrToDate(const S: string; const AFormatSettings: TFormatSettings): TDateTime; overload;
function StrToDateDef(const S: string; const Default: TDateTime): TDateTime; overload; inline;
function StrToDateDef(const S: string; const Default: TDateTime; const AFormatSettings: TFormatSettings): TDateTime; overload;
function TryStrToDate(const S: string; out Value: TDateTime): Boolean; overload; inline;
function TryStrToDate(const S: string; out Value: TDateTime; const AFormatSettings: TFormatSettings): Boolean; overload;
function StrToTime(const S: string): TDateTime; overload; inline;
function StrToTime(const S: string; const AFormatSettings: TFormatSettings): TDateTime; overload;
function StrToTimeDef(const S: string; const Default: TDateTime): TDateTime; overload; inline;
function StrToTimeDef(const S: string; const Default: TDateTime; const AFormatSettings: TFormatSettings): TDateTime; overload;
function TryStrToTime(const S: string; out Value: TDateTime): Boolean; overload; inline;
function TryStrToTime(const S: string; out Value: TDateTime; const AFormatSettings: TFormatSettings): Boolean; overload;
function StrToDateTime(const S: string): TDateTime; overload; inline;
function StrToDateTime(const S: string; const AFormatSettings: TFormatSettings): TDateTime; overload;
function StrToDateTimeDef(const S: string; const Default: TDateTime): TDateTime; overload; inline;
function StrToDateTimeDef(const S: string; const Default: TDateTime; const AFormatSettings: TFormatSettings): TDateTime; overload;
function TryStrToDateTime(const S: string; out Value: TDateTime): Boolean; overload; inline;
function TryStrToDateTime(const S: string; out Value: TDateTime; const AFormatSettings: TFormatSettings): Boolean; overload;
//：：：在使用TFormatSettings时，应当注意考虑其全局变量和局部变量使用的线程安全问题！！！：：：
procedure DateTimeToString(var Result: string; const Format: string; DateTime: TDateTime); overload; inline;
procedure DateTimeToString(var Result: string; const Format: string; DateTime: TDateTime; const AFormatSettings: TFormatSettings); overload;
const
MinDateTime: TDateTime = -657434.0; { 01/01/0100 12:00:00.000 AM }
MaxDateTime: TDateTime = 2958465.99999; { 12/31/9999 11:59:59.999 PM }
function FloatToDateTime(const Value: Extended): TDateTime;
function TryFloatToDateTime(const Value: Extended; out AResult: TDateTime): Boolean;
2.6.2、日期时间格式化记录（结构体）TFormatSettings的格式化字符串Format：
{ FormatDateTime formats the date-and-time value given by DateTime using the
format given by Format. The following format specifiers are supported:
c Displays the date using the format given by the ShortDateFormat
global variable, followed by the time using the format given by
the LongTimeFormat global variable. The time is not displayed if
the fractional part of the DateTime value is zero.
d Displays the day as a number without a leading zero (1-31).
dd Displays the day as a number with a leading zero (01-31).
ddd Displays the day as an abbreviation (Sun-Sat) using the strings
given by the ShortDayNames global variable.
dddd Displays the day as a full name (Sunday-Saturday) using the strings
given by the LongDayNames global variable.
ddddd Displays the date using the format given by the ShortDateFormat
global variable.
dddddd Displays the date using the format given by the LongDateFormat
global variable.
g Displays the period/era as an abbreviation (Japanese and
Taiwanese locales only).
gg Displays the period/era as a full name.
e Displays the year in the current period/era as a number without
a leading zero (Japanese, Korean and Taiwanese locales only).
ee Displays the year in the current period/era as a number with
a leading zero (Japanese, Korean and Taiwanese locales only).
m Displays the month as a number without a leading zero (1-12). If
the m specifier immediately follows an h or hh specifier, the
minute rather than the month is displayed.
mm Displays the month as a number with a leading zero (01-12). If
the mm specifier immediately follows an h or hh specifier, the
minute rather than the month is displayed.
mmm Displays the month as an abbreviation (Jan-Dec) using the strings
given by the ShortMonthNames global variable.
mmmm Displays the month as a full name (January-December) using the
strings given by the LongMonthNames global variable.
yy Displays the year as a two-digit number (00-99).
yyyy Displays the year as a four-digit number (0000-9999).
h Displays the hour without a leading zero (0-23).
hh Displays the hour with a leading zero (00-23).
n Displays the minute without a leading zero (0-59).
nn Displays the minute with a leading zero (00-59).
s Displays the second without a leading zero (0-59).
ss Displays the second with a leading zero (00-59).
z Displays the millisecond without a leading zero (0-999).
zzz Displays the millisecond with a leading zero (000-999).
t Displays the time using the format given by the ShortTimeFormat
global variable.
tt Displays the time using the format given by the LongTimeFormat
global variable.
am/pm Uses the 12-hour clock for the preceding h or hh specifier, and
displays 'am' for any hour before noon, and 'pm' for any hour
after noon. The am/pm specifier can use lower, upper, or mixed
case, and the result is displayed accordingly.
a/p Uses the 12-hour clock for the preceding h or hh specifier, and
displays 'a' for any hour before noon, and 'p' for any hour after
noon. The a/p specifier can use lower, upper, or mixed case, and
the result is displayed accordingly.
ampm Uses the 12-hour clock for the preceding h or hh specifier, and
displays the contents of the TimeAMString global variable for any
hour before noon, and the contents of the TimePMString global
variable for any hour after noon.
/ Displays the date separator character given by the DateSeparator
global variable.
: Displays the time separator character given by the TimeSeparator
global variable.
'xx' Characters enclosed in single or double quotes are displayed as-is,
"xx" and do not affect formatting.
Format specifiers may be written in upper case as well as in lower case
letters--both produce the same result.
If the string given by the Format parameter is empty, the date and time
value is formatted as if a 'c' format specifier had been given.
The following example:
S := FormatDateTime('"The meeting is on" dddd, mmmm d, yyyy, ' +
'"at" hh:mm AM/PM', StrToDateTime('2/15/95 10:30am'));
assigns 'The meeting is on Wednesday, February 15, 1995 at 10:30 AM' to
the string variable S. }
function FormatDateTime(const Format: string; DateTime: TDateTime): string; overload; inline;
function FormatDateTime(const Format: string; DateTime: TDateTime; const AFormatSettings: TFormatSettings): string; overload;
{ System Locale information record }
TSysLocale = packed record
DefaultLCID: TLocaleID; //：本地语言的ID
PriLangID: Integer;
SubLangID: Integer;
FarEast: Boolean;
MiddleEast: Boolean;
end;
{ This is used by TLanguages }
TLangRec = packed record
FName: string; //：本地语言的名称
FLCID: TLocaleID; //：本地语言的ID
FExt: string;
FLocaleName: string;
end;
TLanguages = class //：语言类
//.............(内部方法略)
procedure GetFormatSettings; //：特别注意使用时的线程安全性：它获得了SysLocale.DefaultLCID，并通过SysLocale.DefaultLCID改变了全局变量TFormatSettings的值。
function LCIDToCodePage(const ALCID: LCID): Integer; //：通过LCID取得“代码页”
uses System.SysUtils;
2.6.3、Unix日期时间格式与Delphi格式互转
《Unix系统时间格式与delphi系统时间格式的互转》见本博客：https://blog.csdn.net/pulledup/article/details/105715485
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