<!-- TTimeStamp.md --- 
;; 
;; Description: 
;; Author: Hongyi Wu(吴鸿毅)
;; Email: wuhongyi@qq.com 
;; Created: 二 9月 13 19:58:48 2016 (+0800)
;; Last-Updated: 六 1月  5 12:01:04 2019 (+0800)
;;           By: Hongyi Wu(吴鸿毅)
;;     Update #: 2
;; URL: http://wuhongyi.cn -->

# TTimeStamp

```cpp
// The TTimeStamp encapsulates seconds and ns since EPOCH
//
// This extends (and isolates) struct timespec
//    struct timespec
//       {
//          time_t   tv_sec;   /* seconds */
//          long     tv_nsec;  /* nanoseconds */
//       }
//    time_t seconds is relative to Jan 1, 1970 00:00:00 UTC
//
// No accounting of leap seconds is made.
//
// Due to ROOT/CINT limitations TTimeStamp does not explicitly
// hold a timespec struct; attempting to do so means the Streamer
// must be hand written.  Instead we have chosen to simply contain
// similar fields within the private area of this class.
//
// NOTE: the use of time_t (and its default implementation as a 32 int)
//       implies overflow conditions occurs somewhere around
//       Jan 18, 19:14:07, 2038.
//       If this experiment is still going when it becomes significant
//       someone will have to deal with it.
```


## class

```cpp
   // empty ctor (builds current time with nsec field incremented from static)
   TTimeStamp();

   // construction from timespec struct
   TTimeStamp(const timespec_t &ts) :
      fSec(Int_t(ts.tv_sec)), fNanoSec(ts.tv_nsec) { NormalizeNanoSec(); }

   // construction from time_t and separate nsec
   TTimeStamp(time_t t, Int_t nsec) :
      fSec(Int_t(t)), fNanoSec(nsec) { NormalizeNanoSec(); }

   // construction from bits and pieces
   TTimeStamp(UInt_t year, UInt_t month,
              UInt_t day,  UInt_t hour,
              UInt_t min,  UInt_t sec,
              UInt_t nsec = 0, Bool_t isUTC = kTRUE, Int_t secOffset = 0);

   // compatibility with TDatime
   TTimeStamp(UInt_t date, UInt_t time, UInt_t nsec,
              Bool_t isUTC = kTRUE, Int_t secOffset = 0);

   // compatability with time() and DOS date
   TTimeStamp(UInt_t tloc, Bool_t isUTC = kTRUE, Int_t secOffset = 0,
              Bool_t dosDate = kFALSE);

   virtual ~TTimeStamp() { }

   // initialize to current time with nsec field incremented from static
   void Set();

   // construction from bits and pieces
   void Set(Int_t year, Int_t month,  Int_t day,
            Int_t hour, Int_t min,    Int_t sec,
            Int_t nsec, Bool_t isUTC, Int_t secOffset);

   // compatibility with TDatime
   void Set(Int_t date,   Int_t time, Int_t nsec,
            Bool_t isUTC, Int_t secOffset);

   // compatability with time() and DOS date
   void Set(UInt_t tloc, Bool_t isUTC, Int_t secOffset, Bool_t dosDate);

   // direct setters
   void SetSec(Int_t sec) { fSec = sec; }
   void SetNanoSec(Int_t nsec) { fNanoSec = nsec; }

   timespec_t   GetTimeSpec() const
      { timespec_t value = {fSec,fNanoSec}; return value; }
   time_t       GetSec() const { return fSec; }
   Int_t        GetNanoSec() const { return fNanoSec; }

   Double_t     AsDouble() const { return fSec + 1e-9 * fNanoSec; }
   Double_t     AsJulianDate() const { return (AsDouble()/86400.0 + 2440587.5); }

   // return stored time values converted to sidereal time
   Double_t     AsGMST(Double_t UT1Offset = 0 /*milliseconds*/) const; //rval in hours
   Double_t     AsGAST(Double_t UT1Offset = 0 /*milliseconds*/) const; //rval in hours
   Double_t     AsLMST(Double_t Longitude /*degrees*/, Double_t UT1Offset = 0 /*milliseconds*/) const; //rval in hours
   Double_t     AsLAST(Double_t Longitude /*degrees*/, Double_t UT1Offset = 0 /*milliseconds*/) const; //rval in hours

   const char  *AsString(const Option_t *option="") const;

   void         Copy(TTimeStamp &ts) const;
   UInt_t       GetDate(Bool_t inUTC = kTRUE, Int_t secOffset = 0,
                        UInt_t *year = 0, UInt_t *month = 0,
                        UInt_t *day = 0) const;
   UInt_t       GetTime(Bool_t inUTC = kTRUE, Int_t secOffset = 0,
                        UInt_t *hour = 0, UInt_t *min = 0,
                        UInt_t *sec = 0) const;
   Int_t        GetDayOfYear(Bool_t inUTC = kTRUE, Int_t secOffset = 0) const;
   Int_t        GetDayOfWeek(Bool_t inUTC = kTRUE, Int_t secOffset = 0) const;
   Int_t        GetMonth(Bool_t inUTC = kTRUE, Int_t secOffset = 0) const;
   Int_t        GetWeek(Bool_t inUTC = kTRUE, Int_t secOffset = 0) const;
   Bool_t       IsLeapYear(Bool_t inUTC = kTRUE, Int_t secOffset = 0) const;

   void         Add(const TTimeStamp &offset);

   void         Print(const Option_t *option="") const;

   operator double() const { return AsDouble(); }

   // Utility functions
   static Int_t   GetZoneOffset();
   static time_t  MktimeFromUTC(tm_t *tmstruct);
   static void    DumpTMStruct(const tm_t &tmstruct);
   static Int_t   GetDayOfYear(Int_t day, Int_t month, Int_t year);
   static Int_t   GetDayOfWeek(Int_t day, Int_t month, Int_t year);
   static Int_t   GetWeek(Int_t day, Int_t month, Int_t year);
   static Bool_t  IsLeapYear(Int_t year);
```

## code


## example


<!-- TTimeStamp.md ends here -->