Date Class

Cet ensemble se compose de deux classes destinées à la réalisation des calculs avec des dates et des heures.
une classe de manipulation de dates et un autre pour manipuler les data spans.

Les classes permettent d'ajouter ou de soustraire des périodes de dates et de calculer la différence entre deux dates pour les différentes périodes. Les périodes ans, trimestres, mois, semaines, jours de semaine, heures, minutes, secondes.

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<?php
/******************************************************************************/
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/*                / _ \/ _ \/ _ \_\ \/ _ \/ // / __/ __/ -_|_-<               */
/*               / .__/_//_/ .__/___/\___/\_,_/_/  \__/\__/___/               */
/*              /_/       /_/                                                 */
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/******************************************************************************/
/*                                                                            */
/* Titre          : Date Class                                                */
/*                                                                            */
/* URL            : http://www.phpsources.org/scripts482-PHP.htm              */
/* Auteur         : freemh                                                    */
/* Date édition   : 06 Jan 2009                                               */
/* Website auteur : http://www.tutoslinux.com                                 */
/*                                                                            */
/******************************************************************************/

//===========================================================================
//  DateClass
//
//	Author:		Steve Powell info@scrimpnet.com
//	Licensing:	GNU Lesser General Public License
//	Date:		Copyright (c) 2004 scrimpnet.com
//
//	Please feel free to email me with any questions, suggestions, or problems.
//
//	Public member functions.  See member function comments for more complete
//	documentation.
//
//	SetDate()	DateClass	set class to a specific date/time	
//	DatePart()	mixed		return specific part of the date class
//	Add()		adjust date by months, days, years, hours, minutes, seconds
//	Year()		integer		return class year
//	Month()		integer		return class month (1-12)
//	Day()		integer		return class day of month (1-31)
//	Hours()		integer		return class hour (0-23)		
//	Minutes()	integer		return class minutes (0-59)
//	Seconds()	integer		return class seconds (0-59)
//	TimeStamp()	integer		return PHP base timestamp for class
//	BOW()		DateClass	return first day of week in new DateClass
//	EOW()		DateClass	return last day of week in new DateClass
//	BOM()		DateClass	return first day of month in new DateClass
//	EOM()		DateClass	return last day of month in new DateClass
//	Quarter()	Integer	        return quarter (1-4) for class
//	BOQ()		DateClass	return beginning of quarter in new DateClass
//	EOQ()		DateClass	return end of quarter in new DateClass
//	BOY()		DateClass	return beginning of year in new DateClass
//	EOY()		DateClass	return end of year in new DateClass
//	ToString()	DateClass	return a formatted date/time string
//	UTC()		DateClass	return UTC date/time in new DateClass
//
//	Most functions take an optional <$dateTime> parameter.  If this parameter is

//	used it will adjust the class value to <$dateTime> before performing the
//	requested action.  <$dateTime> can be:
//		string		14-JAN-2004		any format that can be parsed by PHP.strtotime()
//					5/15/2004			using the GNU date syntax.  These are only
//					2004-03-12 17:35    examples
//		integer		1072879687		PHP timestamp
//		object		(DateClass)		existing date class
//
// CUSTOMIZATION HINTS/IDEAS
//	(1)	The _parseDate() function is responsible for taking input and converting

//		it into a PHP timestamp value.  Modify this routine to allow class to
//		be able to handle more date formats
//	(2)	Expand class to have better UTC or timezone awareness
//	(3)	Allow class to handle years that begin on different months
//		i.e. Fiscal year starting 4/1/xxxx or 10/1/xxxx
//
// NOTES
//	(1)	This source code contains many functions you may not need and it
//		contains thorough comments.  You are free to remove any you
//		don't need but you may not remove the licensing or copyright information.
//
// LICENSING
//	This library is free software; you can redistribute it and/or
//	modify it under the terms of the GNU Lesser General Public
//	License as published by the Free Software Foundation; either
//	version 2.1 of the License, or (at your option) any later version.
//
//	This library is distributed in the hope that it will be useful,
//	but WITHOUT ANY WARRANTY; without even the implied warranty of
//	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
//	Lesser General Public License for more details.
//
//	You should have received a copy of the GNU Lesser General Public
//	License along with this library; if not, write to the Free Software
//	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//		
//=============================================================================

class DateClass
{
    //----------------------------
    // private member variables
    //----------------------------
    var $_Date;      //base timestamp value for this class
    var $_datePart; // array of returned by getdate($_Date)
    var $_format;   // last format passed to ToString()
    
    //========================================================
    // constructor
    //========================================================
    function DateClass($dateTime="")
    {
        $this->_format = "Y-m-d H:i:s";
        if (!$dateTime) 
            $this->SetDate(time());
        else
            $this->SetDate($dateTime);
    } //constructor()
    
    //========================================================
    //$this->SetDate
    //
    //	Take <$dateTime> and attempt to convert it into a 
    //	timestamp variable.  If a string then string must
    //	be in standard format.  If an integer it must be
    //	a valid timestamp variable.  If nothing is passed
    //	defaults to current time.
    //
    //  NOTE:  the entire class depends on parsing $dateTime
    //		   correctly.  This is the only place where the
    //		   private timestamp $_Date is directly modified.
    //========================================================
    function SetDate($dateTime="")
    {
        $oldStamp = $this->TimeStamp();
        
        //---------------------------------------------------
        // try to convert $dateTime to a time stamp
        //---------------------------------------------------		
        if ($dateTime=="") 
            $this->_Date=time();
        else
            $this->_Date = $this->_parseDate($dateTime);
        
        //---------------------------------------------------
        //  parse out date/time components if new timestamp
        //  is different than previous timestamp.  This is
        //	done only once per value so that repeated calls
        //	to member functions do no have to repeatedly 
        //  reparse the timestamp
        //---------------------------------------------------
        if ($oldStamp != $this->TimeStamp())
        {
            $this->_datePart = getdate($this->TimeStamp());
        }
        return $this;
    } //SetDate()
    
    //========================================================
    //	_parseDate (private)
    //
    //	Convert $dateTime into a timestamp. 
    //
    //	Return:	timestamp value of <$dateTime>
    //
    //  NOTE:  This is the only place where a date is parsed
    //         into a timestamp.  Modify this routine to 
    //		   accept other types of date/time formats
    //========================================================
    function _parseDate($dateTime="")
    {
        $ts = ; // timestamp of parsed date
        switch(gettype($dateTime))
        {
            case "string": // <== modify to accomodate more date formats
                $ts=strtotime($dateTime);    
                break;
            case "integer":
                $ts=$dateTime;
                break;
            case "object":
                if (get_class($dateTime) == "dateclass")
                {
                    $ts = $dateTime->TimeStamp();
                }
        } //switch				
        return $ts;
    } //_parseDate()
    
    //=========================================================
    // DatePart
    //
    //	Returns specific part of current date/time of class.
    //  If $dateTime is passed then $dateTime replaces value
    //	of class.
    //
    //	$datePart must conform to valid parameters of getdate()
    //		seconds		mday		year		yday
    //		minutes		wday		month		
    //		hours		weekday		mon			timestamp
    //=========================================================
    function DatePart($datePart="",$dateTime="")
    {
        if ($dateTime) $this->SetDate($dateTime);
        if ($datePart=="timestamp") $datePart = ;
        return $this->_datePart[$datePart];
    } //DatePart()
    
    //=========================================================
    //  Retrieve parts of date structure
    //=========================================================	
    function Year($dateTime="")
    {
        if ($dateTime) $this->SetDate($dateTime);
        return $this->DatePart("year");
    }
    function Month($dateTime="")
    {
        if ($dateTime) $this->SetDate($dateTime);
        return $this->DatePart("mon");
    }
    function Day($dateTime="")
    {
        if ($dateTime) $this->SetDate($dateTime);
        return $this->DatePart("mday");
    }
    function Hours($dateTime="")
    {
        if ($dateTime) $this->SetDate($dateTime);
        return $this->DatePart("hours");
    }
    function Minutes($dateTime="")
    {
        if ($dateTime) $this->SetDate($dateTime);
        return $this->DatePart("minutes");
    }
    function Seconds($dateTime="")
    {
        if ($dateTime) $this->SetDate($dateTime);
        return $this->DatePart("seconds");
    }
    
    //===========================================================
    //  Add()
    //
    //	Adjusts <$adjustPart> of class date by <$adustValue>.
    //
    //	Return a reference to this class that contains adjusted 
    //	timestamp.
    //
    //	<$datePart>	string	part of date to adjust.  The parameter
    //						can use any class defined variables
    //						and most of corresponding keys from
    //						the date() and getdate() functions.
    //	
    //						"year" | "years" | "y"
    //						"months" | "month" | "mon"
    //						"days" | "day" | "mday" | "d"
    //						"hours" | "hour" | "g" | 
    //						"minutes" | "minute" | "i"
    //						"seconds" | "second" | "s"
    //	<$adjustValue> int	Amount to adjust date by.  Use negative
    //						to move backwards in time. 
    //===========================================================
    function Add($datePart,$adjustValue,$dateTime="") 
    {
        if ($dateTime) $this->SetDate($dateTime);
        if (!is_int($adjustValue)) $adjustValue = ;
        
        $year = $this->Year();
        $month = $this->Month();
        $day = $this->Day();
        $hour = $this->Hours();
        $min = $this->Minutes();
        $sec = $this->Seconds();
        
        switch(strtolower($datePart))
        {
        case "months":
        case "month": // month
        case "mon":   
             $this->SetDate(mktime($hour,$min,$sec,$month+$adjustValue,$day, 
$year));
            break;
        case "day": // day
        case "days":
        case "d":
        case "mday":
            $this->SetDate(mktime($hour,$min,$sec,$month,$day+$adjustValue, 
$year));
            break;
        case "year": // year
        case "years":
        case "y":
            $this->SetDate(mktime($hour,$min,$sec,$month,$day, $year+
$adjustValue));
            break;
        case "hours": // hour
        case "hour":
        case "g": case "G": case "H": case "h":
            $this->SetDate(mktime($hour+$adjustValue,$min,$sec,$month,$day, 
$year));
            break;
        case "minutes": // minute
        case "minute":
        case "i":
            $this->SetDate(mktime($hour,$min+$adjustValue,$sec,$month,$day, 
$year));
            break;
        case "seconds": // seconds
        case "second":
        case "s":
            $this->SetDate(mktime($hour,$min,$sec+$adjustValue,$month,$day, 
$year));
            break;
        } //switch
        return $this;
    } //Add()
    
    //===========================================================
    // TimeStamp()
    //
    //	Return timestamp value this class represents.
    //
    //	NOTE:	This is the only place the class reads _Date directly
    //===========================================================
    function TimeStamp($dateTime="")
    {
        if ($dateTime) $this->SetDate($DateTime);
        return $this->_Date;
    } //TimeStamp()
    
    //===========================================================
    // BOW() - Beginning of Week
    //
    //	Return date for first day of week.  If class
    //	has time component that remains the same except it is
    //	now the first day of the week
    //
    //	Returned value is in a new DateClass instance and does 
    //	not modify existing class value
    //===========================================================
    function BOW($dateTime="")
    {
        if ($dateTime) $this->SetDate($DateTime);

$dt = new DateClass($this->TimeStamp());
        $wday = $dt->DatePart("wday");
        $wday = $wday*-1;
        $dt->Add("mday",$wday);
        return $dt;
    } //BOW()
    
    //===========================================================
    // EOW() - End of Week
    //
    //	Return date for last day of the week.  If class
    //	has time component that remains the same except it is
    //	now the last day of the week
    //
    //	Returned value is in a new DateClass instance and does 
    //	not modify existing class value
    //===========================================================
    function EOW($dateTime="")
    {
        if ($dateTime) $this->SetDate($DateTime);
        $dt = new DateClass($this->TimeStamp());
        return $dt->Add("day",6-$dt->DatePart("wday"));
    }
    
    //===========================================================
    // BOM() - Beginning of Month
    //	
    //	Return first day of month for the class date.  If class
    //	has time component that remains the same except it is
    //	now the first day of the month
    //
    //	Returned value is in a new DateClass instance and does 
    //	not modify existing class value
    //===========================================================
    function BOM($dateTime="")
    {    
        if ($dateTime) $this->SetDate($DateTime);
        $dt = new DateClass($this->TimeStamp());
        
        $dt->Add("day",-1*($dt->Day()));    
        return $dt;
    } //BOM()
    
    //===========================================================
    // EOM() - End of Month
    //
    //	Return last day of month for the class date.  If class
    //	has time component that remains the same except it is
    //	now the last day of the month
    //
    //	Returned value is in a new DateClass instance and does 
    //	not modify existing class value
    //===========================================================
    function EOM($dateTime="")
    {
        if ($dateTime) $this->SetDate($DateTime);
        $dt = new DateClass($this->TimeStamp());
        $dt->Add("month",1);
        $dtBOM=$dt->BOM();
        $dtBOM->Add("day",-1);
        return $dtBOM;
    } //EOM()
    
    //===========================================================
    // BOY() - Beginning of Year
    //
    //	Return first day of year.  If class
    //	has time component that remains the same except it is
    //	now the first day of the year
    //
    //	Returned value is in a new DateClass instance and does 
    //	not modify existing class value
    //===========================================================
    function BOY($dateTime="")
    {
        if ($dateTime) $this->SetDate($DateTime);
    
        $dt = new DateClass($this->TimeStamp());
        $dt->Add("month",-1*($dt->Month()-1));
        return $dt->BOM();    
    } //BOY()
    
    //===========================================================
    // EOY() - End of Year
    //
    //	Return last day of year.  If class
    //	has time component that remains the same except it is
    //	now the last day of the year
    //
    //	Returned value is in a new DateClass instance and does 
    //	not modify existing class value
    //===========================================================
    function EOY($dateTime="")
    {
        if ($dateTime) $this->SetDate($dateTime);    
        $dt = new DateClass($this->TimeStamp());
        $dt->Add("year",1);
        $dtEOY = $dt->BOY();
        $dtEOY->Add("day",-1);
        return $dtEOY;
    } //EOY()
    
    //===========================================================
    // Quarter()
    //
    //	Return the quarter (1-4) for current value of the class
    //===========================================================
    function Quarter($qDate="",$dateTime="")
    {
        if ($dateTime) $this->SetDate($dateTime);        
        switch($this->Month())
        {
        case 1: case 2: case 3: return 1;break;
        case 4: case 5: case 6: return 2; break;
        case 7: case 8: case 9: return 3; break;
        case 10: case 11: case 12: return 4;break;
        }
    } //Quarter()
    
    //===========================================================
    // BOQ() - Beginning of Quarter
    //
    //	Return first day of <$quarter> or the quarter of the current
    //	value of the class.  If class
    //	has time component that remains the same except it is
    //	now the first day of the quarter.
    //
    //	<$quarter>	integer		(1-4)		
    //
    //	Returned value is in a new DateClass instance and does 
    //	not modify existing class value
    //===========================================================
    function BOQ($quarter=,$dateTime="")
    {
        if ($dateTime) $this->SetDate($DateTime);
        if (!$quarter) $quarter = $this->Quarter();
        switch($quarter)
        {
            case 1:  $month = 1;break;
            case 2:  $month = 4; break;
            case 3:  $month = 7; break;
            case 4:  $month = 10;break;
        }        
        $dt = new DateClass(mktime($this->Hours(),$this->Minutes(),$this->
Seconds(),$month,1,$this->Year()));
        return $dt;
    } //BOQ()
    
    //===========================================================
    // EOQ() - End of Quarter
    //
    //	Return last day of <$quarter> or the quarter of the current
    //	value of the class.  If class
    //	has time component that remains the same except it is
    //	now the last day of the quarter.
    //
    //	<$quarter>	integer		(1-4)
    //
    //	Returned value is in a new DateClass instance and does 
    //	not modify existing class value
    //===========================================================
    function EOQ($quarter=,$dateTime="")
    {
        if ($dateTime) $this->SetDate($DateTime);

if (!$quarter) $quarter = $this->Quarter();
        $month = $quarter*3;
        $dt = new DateClass(mktime($this->Hours(),$this->Minutes(),$this->
Seconds(),$month,1,$this->Year()));
        $month = $dt->EOM();
        return $month;            
    } //EOQ()

//===========================================================
    // ToString()
    //
    // Return a formated string of the current date.  Use
    // <$format> if provided otherwise use
    // the format last passed to this function or use default.
    //
    //	You can pass the following for commonly predefined <$format> types:
    //		RFC822		Mon, 17 May 2004 20:55:42 -0400
    //		RSS_1.0		2004-05-17T20:55:42-0400
    //		HTTP		Mon, 17 May 2004 20:55:42 GMT
    //		
    // Note: <$format> must be compatible with the PHP.date() function
    //===========================================================
    function ToString($format="",$dateTime="")
    {
        if ($dateTime) $this->SetDate($dateTime);
        if($format!="") $this->_format = $format;
        switch (strtoupper($format))
        {
            case "RFC822": return date("r",$this->TimeStamp());
            case "RSS_1.0": case "dc:date":
                return date("Y-m-d\TH:i:sO",$this->TimeStamp());
            case "HTTP": case "RFC1123":
                return date('D, d M Y H:i:s \G\M\T',$this->TimeStamp());
        }
        return date($this->_format,$this->TimeStamp());
    } //ToString()
    
    //===========================================================
    // UTC()
    //
    //	Return UTC equivelent time for class date value.
    //
    //	Returned value is in a new DateClass instance and does 
    //	not modify existing class value
    //============================================================
    function UTC($dateTime="")
    {
        if ($dateTime) $this->SetDate($dateTime);
        $dt = date($this);
        $dt->Add("minutes",date("Z",$this->TimeStamp()));
        return $dt;
    } // UTC()
    
} //class DateClass

//===========================================================================
//  DateSpan Class
//
//	Author:		Steve Powell info@scrimpnet.com
//	Licensing:	GNU Lesser General Public License
//	Date:		(c) 2004 ScrimpNet.com
//
//	Please feel free to email me with any questions, suggestions, or problems.
//
//	This class determines the span of time between two different date/times.
//
//	Functions return positive value when StartDate < StopDate.  Functions
//	return negative values when StartDate > StopDate.
//
//	Generally date parameters can take the form of:
//	string		"3/14/2004"		any GNC compatible strtotime() format
//	integer		173218828		PHP time stamp
//	object		object			DateClass
//	
//	Prerequisites:	requires DateClass
//
//	Public member functions. See member function comments for more complete
//	complete descriptions:
//	DateSpanClass()			constructor
//
//	StartDate				(property) return DateClass of starting date in span
//	StopDate				(property) return DateClass of stopping date in span
//
//	Years()					return number of years covered in span
//	Quarters()				return number of quarters covered in span
//	Months()				return number of months covered in span
//	Weeks()					return number of weeks covered in span
//	WeekDays()				return number of week days (M-F) in span
//	Days()					return number of days covered in span
//	Hours()					return number of hours covered in span
//	Minutes()				return number of minutes covered in span
//	Seconds()				return number of seconds covered in span
//	Span()					return number of periods between two dates
//	ToString()				return formatted string representing span
//	TimeStamp()				return PHP timestamp for span (same of Seconds())
//
// NOTES:
//	(1)	This source code contains many functions you may not need and it
//		contains thorough comments.  You are free to remove any you
//		don't need but you may not remove the licensing or copyright information.
//	(2)	For performance reasons, multiple calls to the class with the same
//  	span-start/span-stop dates (and/or times) are not recalculated.
//
// CUSTOMIZATION IDEAS
//	(1)	Expand class to be able to handle UTC and spans between time zones
//	(2)	Add capability to handle fiscal years that do not correlate 
//		to calendar years. i.e. years that begin on 4/1 or 10/1 etc.
//	
// LICENSING
//	This library is free software; you can redistribute it and/or
//	modify it under the terms of the GNU Lesser General Public
//	License as published by the Free Software Foundation; either
//	version 2.1 of the License, or (at your option) any later version.
//
//	This library is distributed in the hope that it will be useful,
//	but WITHOUT ANY WARRANTY; without even the implied warranty of
//	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
//	Lesser General Public License for more details.
//
//	You should have received a copy of the GNU Lesser General Public
//	License along with this library; if not, write to the Free Software
//	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
//===========================================================================	
class DateSpanClass
{
    //------------------------------------------------------
    // public member variables (READ ONLY)
    //------------------------------------------------------
    var $StartDate;
    var $StopDate;
    
    //-------------------------------------------------------
    // private member variables
    //-------------------------------------------------------
    var    $_months;
    var $_days;
    var $_weekdays;
    var $_hours;
    var $_minutes;
    var $_seconds;
    var    $_weeks; 
    var $_quarters;
    var $_format; 
    var $_years;
    var $_spandir; // 1 = positive span, -1 = negative span
            
    //=========================================================
    // constructor()
    //
    //	Normally class is instantiated without any parameters.
    //	Span dates are usually supplied via Span() or property
    //	accessor functions.
    //=========================================================
    function DateSpanClass($dateStart="",$dateStop="")
    {
        $this->_reset();
        if (!$dateStart) $dateStart = new DateClass();
        if (!$dateStop) $dateStop = new DateClass();    
        $this->Span("seconds",$dateStart,$dateStop);        
    } //constructor()
    
    //==========================================================
    //	_reset	(private)
    //
    //	Set class member variables to known state
    //==========================================================
    function _reset()
    {
        $this->_format = "m-d-y h:i:s";
        $this->_years=;
        $this->_months=;
        $this->_days=;
        $this->_hours=;
        $this->_minutes=;
        $this->_seconds=;
        $this->_weeks=; 
        $this->_quarters=;
        $this->_weekdays=;
        $this->_spandir=1;
    } //_reset()
    
    //==========================================================
    //  property accessor functions
    //
    //	optional parameters will calculate
    //	span between <$dateStart> and <$dateStop>.  The span of the
    //	class will change based on these parameters. Existing
    //	class values are used if parameters
    //	are not set.
    //
    //	$dateX parameter can be:
    //		string		"4/13/2004"		or any other GNC compatible format
    //		integer		PHP timestamp
    //		object		DateClass
    //==========================================================
    function Years($dateStart="",$dateStop="")
    {
        if ($dateStart || $dateStop || $this->_years==)  $this->Span("years",
$dateStart,$dateStop);
        return $this->_years;
    }
    function Months($dateStart="",$dateStop="")
    {
        if ($dateStart || $dateStop || $this->_months==) $this->Span("months",
$dateStart,$dateStop);    
        return $this->_months;
    }
    function WeekDays($dateStart="",$dateStop="")
    {
        if ($dateStart || $dateStop || $this->_weekdays==) $this->Span(
"weekdays",$dateStart,$dateStop);
        return $this->_weekdays;
    }
    function Days($dateStart="",$dateStop="")
    {
        if ($dateStart || $dateStop || $this->_days==) $this->Span("days",
$dateStart,$dateStop);
        return $this->_days;
    }
    function Weeks($dateStart="",$dateStop="")
    {
        if ($dateStart || $dateStop || $this->_weeks==) $this->Span("weeks",
$dateStart,$dateStop);
        return $this->_weeks;
    }
    function Quarters($dateStart="",$dateStop="")
    {
        if ($dateStart || $dateStop || $this->_quarters==) $this->Span(
"quarters",$dateStart,$dateStop);
        return $this->_quarters;
    }
    function Hours($dateStart="",$dateStop="")
    {
        if ($dateStart || $dateStop || $this->_hours==) $this->Span("hours",
$dateStart,$dateStop);
        return $this->_seconds();
    }
    function Minutes($dateStart="",$dateStop="")
    {
        if ($dateStart || $dateStop || $this->_minutes==) $this->Span("minutes",
$dateStart,$dateStop);
        return $this->_minutes();
    }
    function Seconds($dateStart="",$dateStop="")
    {
        if ($dateStart || $dateStop || $this->_seconds==) $this->Span("seconds",
$dateStart,$dateStop);
        return $this->_seconds;
    }
    
    //=========================================================
    // Span()
    //
    //	Calculate span between two dates.  Returned value is
    //	determined by <$datePart>.  Numbers could be integer
    //	or float depending on span result.
    //
    //	<$datePart>	string	part of date to adjust.  The parameter
    //						can use any the class defined variables
    //						and most of corresponding keys from
    //						the date() and getdate() functions.
    //						"year" | "years" | "y"
    //						"quarters" | "q"
    //						"months" | "month" | "mon"
    //						"weeks" | "w"
    //						"days" | "day" | "mday" | "d"
    //						"hours" | "hour" | "g" | 
    //						"minutes" | "minute" | "i"
    //						"seconds" | "second" | "s"
    //
    //	<$dateStart>,<$dateStop>	begin/end dates for time span
    //						string "5/23/2004"		formated GNC date
    //						integer	393922923		timestamp
    //						object	DateClass
    //=========================================================
    function Span($period,$dateStart="",$dateStop="")
    {
        //--------------------------------------------------
        //  create new span if parameters provided
        //--------------------------------------------------
        if ($dateStart)
            $this->StartDate = new DateClass($dateStart);
        if ($dateStop)
            $this->StopDate = new DateClass($dateStop);
        
        //--------------------------------------------------
        //	check to see if we are going to be using a
        //	negative span (stop date is before start date)
        //--------------------------------------------------
        $this->_spandir = 1;
        if ($this->StartDate->TimeStamp() > $this->StopDate->TimeStamp())
        {
            $this->_spandir = -1;
        }

//--------------------------------------------------
        //	calculate fixed length intervals
        //--------------------------------------------------
        $this->_seconds = $this->StopDate->TimeStamp()-$this->StartDate->
TimeStamp();
        $this->_minutes = $this->_seconds/60;
        $this->_hours = $this->_minutes/60;
        $this->_days = $this->_hours/24;
        $this->_years = $this->_days/365.25;
    
        //--------------------------------------------------
        //	return user requested period
        //--------------------------------------------------
        switch(strtolower($period))
        {
        case "years": case "year": case "y":
            return $this->_years;break;
        case "quarters": case "q":
            return $this->_calcQuarters();break;
        case "months": case "mon": case "m": case "month":
            return $this->_calcMonths();break;
        case "weeks": case "w":
            return $this->_calcWeeks();break;
        case "weekdays": case "wdays":
            return $this->_calcWeekDays();break;
        case "days": case "d": case "day":
            return $this->_days;break;
        case "hours": case "hour": case "h": case "g":
            return $this->_hours;break;
        case "minutes": case "minute": case "i":
            return $this->_minutes;break;
        case "seconds": case "second": case "s":
            return $this->_seconds;break;
        }
        return ; // invalid period parameter
    } //span()
    
    //========================================================
    // _calcQuarters  (private)
    //
    //	Return number of quarter boundries crossed in the 
    //	span.  This is a private function and should only
    //	be called from within the class.  Use other accessor
    //	functions to access the information returned from 
    //	here.
    //========================================================
    function _calcQuarters()
    {
        if ($this->_spandir==1) // start is before stop (positive span)
        {
            $dtStart = new DateClass($this->StartDate);
            $dtStart = $dtStart->BOQ();
            $dtStop = $this->StopDate;
        }
        else
        {
            $dtStart = new DateClass($this->StopDate);
            $dtStart = $dtStart->BOQ();
            $dtStop = $this->StartDate;
        }
        
        //--------------------------------------------------
        //	count times crossing period boundries
        //--------------------------------------------------
        $counter =;
        while ($dtStart->TimeStamp() < $dtStop->TimeStamp())
        {
            $counter++;            
            $dtStart->Add("month",3);
        }
        $this->_quarters = ($counter-1*$this->_spandir);
        
        return $this->_quarters;

} //_calcQuarters()
    
    //===========================================================
    // _calcMonths()
    //
    //	Return number of month boundries crossed in the span.  This
    //	is a private function and should only be called from within
    //	the class.  Use other accessor functions to access the
    //	information returned from this function.
    //===========================================================
    function _calcMonths()
    {
        if ($this->_spandir==1) // start is before stop (positive span)
        {
            $dtStart = new DateClass($this->StartDate);
            $dtStart = $dtStart->BOM();
            $dtStop = $this->StopDate;
        }
        else
        {
            $dtStart = new DateClass($this->StopDate);
            $dtStart = $dtStart->BOM();
            $dtStop = $this->StartDate;
        }
        
        //--------------------------------------------------
        // count times crossing period boundries
        //--------------------------------------------------
        $counter =;
        while ($dtStart->TimeStamp() < $dtStop->TimeStamp())
        {
            $counter++;            
            $dtStart->Add("month",1);
        }
        $this->_months = ($counter-1)*$this->_spandir;
        
        return $this->_months;
        
    } //_calcMonths()
    
    //===========================================================
    // _calcWeeks()
    //
    //	Return number of week boundries crossed in the span. This
    //	means the number of Sunday's between span dates.
    //
    //	This is a private function and should only be called from within
    //	the class.  Use other accessor functions to access the
    //	information returned from this function.
    //===========================================================
    function _calcWeeks()
    {
        if ($this->_spandir==1) // start is before stop (positive span)
        {
            $dtStart = new DateClass($this->StartDate);
            $dtStart = $dtStart->BOW();
            $dtStop = $this->StopDate;
        }
        else
        {
            $dtStart = new DateClass($this->StopDate);
            $dtStart = $dtStart->BOW();
            $dtStop = $this->StartDate;
        }
        
        //--------------------------------------------------
        //	count times crossing period boundries
        //--------------------------------------------------
        $counter=;
        while ($dtStart->TimeStamp() < $dtStop->TimeStamp())
        {
            $counter++;            
            $dtStart->Add("day",7);
        }
        $this->_weeks = $counter-1;
        $this->_weeks *= $this->_spandir;
        
        return ($this->_weeks);

} //_calcWeeks()
    
    //===========================================================
    // _calcWeekDays()
    //
    //	Return number of week boundries crossed in the span. This
    //	means the number of business days between span dates.
    //
    //	This is a private function and should only be called from within
    //	the class.  Use other accessor functions to access the
    //	information returned from this function.
    //===========================================================
    function _calcWeekDays()
    {
        if ($this->_spandir==1) // start is before stop (positive span)
        {
            $dtStart = new DateClass($this->StartDate);
            $dtStop = $this->StopDate;
        }
        else
        {
            $dtStart = new DateClass($this->StopDate);
            $dtStop = $this->StartDate;
        }
        
        //--------------------------------------------------
        //	count times crossing period boundries
        //--------------------------------------------------
        $counter=;
        while ($dtStart->TimeStamp() < $dtStop->TimeStamp())
        {
            if ($dtStart->DatePart("wday") >  && $dtStart->DatePart("wday") < 5)
                $counter++;            
            $dtStart->Add("day",1);
        }
        $this->_weekdays = $counter;
        $this->_weekdays *= $this->_spandir;
        
        return ($this->_weekdays);

} //_calcWeekDays()
    //===========================================================
    // TimeStamp()
    //
    //	Return timestamp value this class represents.
    //
    //	This class uses the PHP timestamp for all calculations.
    //===========================================================
    function TimeStamp()
    {
        return $this->Seconds();
    }
    
    //=========================================================
    //	ToString()
    //  Return a formated string of the current timestamp.  
    //	Function uses <$format> if provided otherwise it uses
    //  the format last passed to this function or use $_format.
    //
    // Note: <$format> must be compatible with the PHP.date() function
    //=========================================================
    function ToString($format="")
    {
        if ($format) $this->_format = $format;
        return date($this->_format,$this->TimeStamp());
    } //ToString()
    
} //class DateSpan
?>