**Version:*** 1.0 *

**Type:** Function

**Category:** Calendars/Dates

**License:** GNU General Public License

**Description:** Contains two functions, dayofweek() will return the day of the week for a given date (0=Sunday, 1=Monday, etc). nthDayOfMonth() will return the date of the nth weekday of a month (i.e. 2nd Tuesday of April 2001 will return 10).

/* * PHP Day of Week functions * Copyright (c) 2001, Mark Motley <mmotley@la-mirada.net> * GNU Public license, use as you want */ /* * dayofweek($day,$month,$year) will compute the day of the week a * a particular date falls. * * Paramaters: * * $day - Day of month [1-31] * $month - Month [1-12] * $year - The year [1900-?] * * Returns: * * Numerical day of week where 0=Sunday, 1=Monday, etc. * On error (out-of-bounds dates) returns -1. * */ function dayofweek($day,$month,$year) { /* Check date for validity */ if (!checkdate($month,$day,$year)) return -1; $a=(int)((14-$month) / 12); $y=$year-$a; $m=$month + (12*$a) - 2; $retval=($day + $y + (int)($y/4) - (int)($y/100) + (int)($y/400) + (int)((31*$m)/12)) % 7; return $retval; } /* phpdow_mod($a,$b) is a fixed-up modulo function that will deal with * negative numbers properly. PHP's modulo function doesn't, and the * forumulas are dependent on it. * It's really only here to support the nthDayOfMonth() function. */ function phpdow_mod($a,$b) { if ($a <= 0) return (int)phpdow_mod($b-abs($a),$b); else return (int)($a%$b); } /* * nthDayOfMonth($n,$dow,$month,$year) will compute the Nth day of the given * month. For example, the first Monday in April 2001. * * Parameters: * * $n - the Nth day you want, i.e. 2 for 2nd * $dow - The day of week you want, 0=Sunday, 1=Monday, etc. [0-6] * $month - The month you want [1-12] * $year - The full year [1900? - ??] * * Returns: * * The date, in the month you passed, that fits the criteria. * Here we return to error conditions: * -1 = invalid date * -2 = There is no Nth day of that month, like no 5th Tuesday * of the specified month * * Example: * * To find the first Tuesday in June 2001: * $day = nthDayInMonth(1,2,6,2001); * will return 4, which means the first Tuesday in June is 6/4/2001. * */ function nthDayOfMonth($n,$dow,$month,$year) { /* Check the date */ if ($month > 12) return -1; if ($dow > 6) return -1; /* Valid Nth day, should be no more than 5 */ if (($n <= 0) || ($n > 5)) return -1; $retval = (7*$n)-6+phpdow_mod($dow-dayofweek(1,$month,$year),7); /* Make sure the date is not greater than the number of days in the month */ if (!checkdate($month,$retval,$year)) return -2; /* Otherwise we return the date */ return $retval; }