SQLite

typedef struct DateTime DateTime;
struct DateTime {
  sqlite3_int64 iJD;  /* The julian day number times 86400000 */
  int Y, M, D;        /* Year, month, and day */
  int h, m;           /* Hour and minutes */
  int tz;             /* Timezone offset in minutes */
  double s;           /* Seconds */
  char validJD;       /* True (1) if iJD is valid */
  char rawS;          /* Raw numeric value stored in s */
  char validYMD;      /* True (1) if Y,M,D are valid */
  char validHMS;      /* True (1) if h,m,s are valid */

  char validTZ;       /* True (1) if tz is valid */
  char tzSet;         /* Timezone was set explicitly */
  char isError;       /* An overflow has occurred */
};


/*

      }
      ms /= rScale;
    }
  }else{
    s = 0;
  }
  p->validJD = 0;
  p->rawS = 0;
  p->validHMS = 1;
  p->h = h;
  p->m = m;
  p->s = s + ms;
  if( parseTimezone(zDate, p) ) return 1;
  p->validTZ = (p->tz!=0)?1:0;
  return 0;

    M = p->M;
    D = p->D;
  }else{
    Y = 2000;  /* If no YMD specified, assume 2000-Jan-01 */
    M = 1;
    D = 1;
  }
  if( Y<-4713 || Y>9999 || p->rawS ){
    datetimeError(p);
    return;
  }
  if( M<=2 ){
    Y--;
    M += 12;
  }

  if( p->iJD>0 ){
    p->validJD = 1;
    return 0;
  }else{
    return 1;
  }
}

/*
** Input "r" is a numeric quantity which might be a julian day number,
** or the number of seconds since 1970.  If the value if r is within
** range of a julian day number, install it as such and set validJD.
** If the value is a valid unix timestamp, put it in p->s and set p->rawS.
*/
static void setRawDateNumber(DateTime *p, double r){
  p->s = r;
  p->rawS = 1;
  if( r>=0.0 && r<5373484.5 ){
    p->iJD = (sqlite3_int64)(r*86400000.0 + 0.5);
    p->validJD = 1;
  }
}

/*
** Attempt to parse the given string into a julian day number.  Return
** the number of errors.
**
** The following are acceptable forms for the input string:
**

  if( parseYyyyMmDd(zDate,p)==0 ){
    return 0;
  }else if( parseHhMmSs(zDate, p)==0 ){
    return 0;
  }else if( sqlite3StrICmp(zDate,"now")==0){
    return setDateTimeToCurrent(context, p);
  }else if( sqlite3AtoF(zDate, &r, sqlite3Strlen30(zDate), SQLITE_UTF8) ){
    setRawDateNumber(p, r);

    return 0;
  }
  return 1;
}

/*
** Return TRUE if the given julian day number is within range.

  p->s = s/1000.0;
  s = (int)p->s;
  p->s -= s;
  p->h = s/3600;
  s -= p->h*3600;
  p->m = s/60;
  p->s += s - p->m*60;
  p->rawS = 0;
  p->validHMS = 1;
}

/*
** Compute both YMD and HMS
*/
static void computeYMD_HMS(DateTime *p){

  y.D = sLocal.tm_mday;
  y.h = sLocal.tm_hour;
  y.m = sLocal.tm_min;
  y.s = sLocal.tm_sec;
  y.validYMD = 1;
  y.validHMS = 1;
  y.validJD = 0;
  y.rawS = 0;
  y.validTZ = 0;
  y.isError = 0;
  computeJD(&y);
  *pRc = SQLITE_OK;
  return y.iJD - x.iJD;
}
#endif /* SQLITE_OMIT_LOCALTIME */

/*

      break;
    }
#endif
    case 'u': {
      /*
      **    unixepoch
      **
      ** Treat the current value of p->s as the number of
      ** seconds since 1970.  Convert to a real julian day number.
      */
      if( strcmp(z, "unixepoch")==0 && p->rawS ){
        double r = p->s*1000.0 + 210866760000000.0;
        if( r>=0.0 && r<464269060800000.0 ){
          clearYMD_HMS_TZ(p);
          p->iJD = (sqlite3_int64)r;
          p->validJD = 1;
          p->rawS = 0;
          rc = 0;
        }
      }
#ifndef SQLITE_OMIT_LOCALTIME
      else if( strcmp(z, "utc")==0 ){
        if( p->tzSet==0 ){
          sqlite3_int64 c1;
          computeJD(p);
          c1 = localtimeOffset(p, pCtx, &rc);

  int eType;
  memset(p, 0, sizeof(*p));
  if( argc==0 ){
    return setDateTimeToCurrent(context, p);
  }
  if( (eType = sqlite3_value_type(argv[0]))==SQLITE_FLOAT
                   || eType==SQLITE_INTEGER ){
    setRawDateNumber(p, sqlite3_value_double(argv[0]));



  }else{
    z = sqlite3_value_text(argv[0]);
    if( !z || parseDateOrTime(context, (char*)z, p) ){
      return 1;
    }
  }
  for(i=1; i<argc; i++){