calc.php

一个基于web的开源项目管理工具

            $month=12;
            $day=1;
        }

        return Date_Calc::dateFormat($day,$month,$year,$format);

    } // end func beginOfPrevMonth

    /**
     * Returns date of the last day of previous month for given date.
     *
     * @param string year in format CCYY, default current local year
     * @param string month in format MM, default current local month
     * @param string day in format DD, default current local day
     * @param string format for returned date
     *
     * @access public
     *
     * @return string date in given format
     */

    function endOfPrevMonth($day="",$month="",$year="",$format="%Y%m%d")
    {
        if(empty($year))
            $year = Date_Calc::dateNow("%Y");
        if(empty($month))
            $month = Date_Calc::dateNow("%m");
        if(empty($day))
            $day = Date_Calc::dateNow("%d");

        if($month > 1)
        {
            $month--;
        }
        else
        {
            $year--;
            $month=12;
        }

        $day = Date_Calc::daysInMonth($month,$year);

        return Date_Calc::dateFormat($day,$month,$year,$format);

    } // end func endOfPrevMonth

    /**
     * Returns date of the next weekday of given date,
     * skipping from Friday to Monday.
     *
     * @param string year in format CCYY, default current local year
     * @param string month in format MM, default current local month
     * @param string day in format DD, default current local day
     * @param string format for returned date
     *
     * @access public
     *
     * @return string date in given format
     */

    function nextWeekday($day="",$month="",$year="",$format="%Y%m%d")
    {
        if(empty($year))
            $year = Date_Calc::dateNow("%Y");
        if(empty($month))
            $month = Date_Calc::dateNow("%m");
        if(empty($day))
            $day = Date_Calc::dateNow("%d");

        $days = Date_Calc::dateToDays($day,$month,$year);

        if(Date_Calc::dayOfWeek($day,$month,$year) == 5)
            $days += 3;
        elseif(Date_Calc::dayOfWeek($day,$month,$year) == 6)
            $days += 2;
        else
            $days += 1;

        return(Date_Calc::daysToDate($days,$format));

    } // end func nextWeekday

    /**
     * Returns date of the previous weekday,
     * skipping from Monday to Friday.
     *
     * @param string year in format CCYY, default current local year
     * @param string month in format MM, default current local month
     * @param string day in format DD, default current local day
     * @param string format for returned date
     *
     * @access public
     *
     * @return string date in given format
     */

    function prevWeekday($day="",$month="",$year="",$format="%Y%m%d")
    {
        if(empty($year))
            $year = Date_Calc::dateNow("%Y");
        if(empty($month))
            $month = Date_Calc::dateNow("%m");
        if(empty($day))
            $day = Date_Calc::dateNow("%d");

        $days = Date_Calc::dateToDays($day,$month,$year);

        if(Date_Calc::dayOfWeek($day,$month,$year) == 1)
            $days -= 3;
        elseif(Date_Calc::dayOfWeek($day,$month,$year) == 0)
            $days -= 2;
        else
            $days -= 1;

        return(Date_Calc::daysToDate($days,$format));

    } // end func prevWeekday

    /**
     * Returns date of the next specific day of the week
     * from the given date.
     *
     * @param int day of week, 0=Sunday
     * @param string year in format CCYY, default current local year
     * @param string month in format MM, default current local month
     * @param string day in format DD, default current local day
     * @param boolean onOrAfter if true and days are same, returns current day
     * @param string format for returned date
     *
     * @access public
     *
     * @return string date in given format
     */

    function nextDayOfWeek($dow,$day="",$month="",$year="",$format="%Y%m%d",$onOrAfter=false)
    {
        if(empty($year))
            $year = Date_Calc::dateNow("%Y");
        if(empty($month))
            $month = Date_Calc::dateNow("%m");
        if(empty($day))
            $day = Date_Calc::dateNow("%d");

        $days = Date_Calc::dateToDays($day,$month,$year);
        $curr_weekday = Date_Calc::dayOfWeek($day,$month,$year);

        if($curr_weekday == $dow)
		{
			if(!$onOrAfter)
            	$days += 7;
		}
        elseif($curr_weekday > $dow)
            $days += 7 - ( $curr_weekday - $dow );
        else
            $days += $dow - $curr_weekday;

        return(Date_Calc::daysToDate($days,$format));

    } // end func nextDayOfWeek

    /**
     * Returns date of the previous specific day of the week
     * from the given date.
     *
     * @param int day of week, 0=Sunday
     * @param string year in format CCYY, default current local year
     * @param string month in format MM, default current local month
     * @param string day in format DD, default current local day
     * @param boolean onOrBefore if true and days are same, returns current day
     * @param string format for returned date
     *
     * @access public
     *
     * @return string date in given format
     */

    function prevDayOfWeek($dow,$day="",$month="",$year="",$format="%Y%m%d",$onOrBefore=false)
    {
        if(empty($year))
            $year = Date_Calc::dateNow("%Y");
        if(empty($month))
            $month = Date_Calc::dateNow("%m");
        if(empty($day))
            $day = Date_Calc::dateNow("%d");

        $days = Date_Calc::dateToDays($day,$month,$year);
        $curr_weekday = Date_Calc::dayOfWeek($day,$month,$year);

        if($curr_weekday == $dow)
		{
			if(!$onOrBefore)
            	$days -= 7;
		}
        elseif($curr_weekday < $dow)
            $days -= 7 - ( $dow - $curr_weekday );
        else
            $days -= $curr_weekday - $dow;

        return(Date_Calc::daysToDate($days,$format));

    } // end func prevDayOfWeek

    /**
     * Returns date of the next specific day of the week
     * on or before the given date.
     *
     * @param int day of week, 0=Sunday
     * @param string year in format CCYY, default current local year
     * @param string month in format MM, default current local month
     * @param string day in format DD, default current local day
     * @param string format for returned date
     *
     * @access public
     *
     * @return string date in given format
     */

    function nextDayOfWeekOnOrAfter($dow,$day="",$month="",$year="",$format="%Y%m%d")
    {
        return(Date_Calc::nextDayOfWeek($dow,$day="",$month="",$year="",$format="%Y%m%d",true));
    } // end func nextDayOfWeekOnOrAfter

    /**
     * Returns date of the previous specific day of the week
     * on or before the given date.
     *
     * @param int day of week, 0=Sunday
     * @param string year in format CCYY, default current local year
     * @param string month in format MM, default current local month
     * @param string day in format DD, default current local day
     * @param string format for returned date
     *
     * @access public
     *
     * @return string date in given format
     */

    function prevDayOfWeekOnOrBefore($dow,$day="",$month="",$year="",$format="%Y%m%d")
    {
        return(Date_Calc::prevDayOfWeek($dow,$day="",$month="",$year="",$format="%Y%m%d",true));

    } // end func prevDayOfWeekOnOrAfter

    /**
     * Returns date of day after given date.
     *
     * @param string year in format CCYY, default current local year
     * @param string month in format MM, default current local month
     * @param string day in format DD, default current local day
     * @param string format for returned date
     *
     * @access public
     *
     * @return string date in given format
     */

    function nextDay($day="",$month="",$year="",$format="%Y%m%d")
    {
        if(empty($year))
            $year = Date_Calc::dateNow("%Y");
        if(empty($month))
            $month = Date_Calc::dateNow("%m");
        if(empty($day))
            $day = Date_Calc::dateNow("%d");

        $days = Date_Calc::dateToDays($day,$month,$year);

        return(Date_Calc::daysToDate($days + 1,$format));

    } // end func nextDay

    /**
     * Returns date of day before given date.
     *
     * @param string year in format CCYY, default current local year
     * @param string month in format MM, default current local month
     * @param string day in format DD, default current local day
     * @param string format for returned date
     *
     * @access public
     *
     * @return string date in given format
     */

    function prevDay($day="",$month="",$year="",$format="%Y%m%d")
    {
        if(empty($year))
            $year = Date_Calc::dateNow("%Y");
        if(empty($month))
            $month = Date_Calc::dateNow("%m");
        if(empty($day))
            $day = Date_Calc::dateNow("%d");

        $days = Date_Calc::dateToDays($day,$month,$year);

        return(Date_Calc::daysToDate($days - 1,$format));

    } // end func prevDay

    /**
     * Sets century for 2 digit year.
     * 51-99 is 19, else 20
     *
     * @param string 2 digit year
     *
     * @access public
     *
     * @return string 4 digit year
     */

    function defaultCentury($year)
    {
        if(strlen($year) == 1)
            $year = "0$year";
        if($year > 50)
            return( "19$year" );
        else
            return( "20$year" );

    } // end func defaultCentury

    /**
     * Returns number of days between two given dates.
     *
     * @param string year in format CCYY
     * @param string month in format MM
     * @param string day in format DD
     * @param string year in format CCYY
     * @param string month in format MM
     * @param string day in format DD
     *
     * @access public
     *
     * @return int absolute number of days between dates,
     *      -1 if there is an error.
     */

    function dateDiff($day1,$month1,$year1,$day2,$month2,$year2)
    {
        if(!Date_Calc::isValidDate($day1,$month1,$year1))
            return -1;
        if(!Date_Calc::isValidDate($day2,$month2,$year2))
            return -1;

        return(abs((Date_Calc::dateToDays($day1,$month1,$year1))
                    - (Date_Calc::dateToDays($day2,$month2,$year2))));

    } // end func dateDiff

    /**
    * Compares two dates
    *
    * @param string $day1   day in format DD
    * @param string $month1 month in format MM
    * @param string $year1  year in format CCYY
    * @param string $day2   day in format DD
    * @param string $month2 month in format MM
    * @param string $year2  year in format CCYY
    *
    * @access public
    * @return int 0 on equality, 1 if date 1 is greater, -1 if smaller
    */
    function compareDates($day1,$month1,$year1,$day2,$month2,$year2)
    {
        $ndays1 = Date_Calc::dateToDays($day1, $month1, $year1);
        $ndays2 = Date_Calc::dateToDays($day2, $month2, $year2);
        if ($ndays1 == $ndays2) {
            return 0;
        }
        return ($ndays1 > $ndays2) ? 1 : -1;
    }

    /**
     * Find the number of days in the given month.
     *
     * @param string month in format MM, default current local month
     *
     * @access public
     *
     * @return int number of days
     */

    function daysInMonth($month="",$year="")
    {
        if(empty($year))
            $year = Date_Calc::dateNow("%Y");
        if(empty($month))
            $month = Date_Calc::dateNow("%m");

        if($month == 2)
        {
            if(Date_Calc::isLeapYear($year))
                return 29;
            else
                return 28;
        }
        elseif($month == 4 or $month == 6 or $month == 9 or $month == 11)
            return 30;
        else
            return 31;
    } // end func daysInMonth