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<?php
// date_functions.php
// functions for returning or comparing dates
// takes Apple's 2 character day format and makes it into 3 characters
function two2threeCharDays($day) {
if ($day == "SU") $day_longer = "sun";
elseif ($day == "MO") $day_longer = "mon";
elseif ($day == "TU") $day_longer = "tue";
elseif ($day == "WE") $day_longer = "wed";
elseif ($day == "TH") $day_longer = "thu";
elseif ($day == "FR") $day_longer = "fri";
elseif ($day == "SA") $day_longer = "sat";
return $day_longer;
}
// dateOfWeek() takes a date in Ymd and a day of week as iCal knows them
// (ie: SU, MO, TU, etc)and returns the date of that day.
// This function may be specific to WEEKLY recurring events.
function dateOfWeek($Ymd, $day) {
global $week_start_day;
if (!$week_start_day) $week_start_day = "Sunday";
$timestamp = strtotime($Ymd);
$sunday = strtotime((date("w",$timestamp)==0 ? "$week_start_day" : "last $week_start_day"), $timestamp);
$day_longer = two2threeCharDays($day);
return date("Ymd",strtotime($day_longer,$sunday));
}
// function to compare to dates in Ymd and return the number of weeks
// that differ between them. requires dateOfWeek()
function weekCompare($now, $then) {
global $week_start_day;
$day = substr($week_start_day, 0, 2);
$sun_now = dateOfWeek($now, $day);
$sun_then = dateOfWeek($then, $day);
$seconds_now = strtotime($sun_now);
$seconds_then = strtotime($sun_then);
$diff_seconds = $seconds_now - $seconds_then;
$diff_minutes = $diff_seconds/60;
$diff_hours = $diff_minutes/60;
$diff_days = round($diff_hours/24);
$diff_weeks = $diff_days/7;
return $diff_weeks;
}
// function to compare to dates in Ymd and return the number of days
// that differ between them. requires dateOfWeek()
function dayCompare($now, $then) {
$seconds_now = strtotime($now);
$seconds_then = strtotime($then);
$diff_seconds = $seconds_now - $seconds_then;
$diff_minutes = $diff_seconds/60;
$diff_hours = $diff_minutes/60;
$diff_days = round($diff_hours/24);
return $diff_days;
}
// function to compare to dates in Ymd and return the number of months
// that differ between them. requires dateOfWeek()
function monthCompare($now, $then) {
ereg ("([0-9]{4})([0-9]{2})([0-9]{2})", $now, $date_now);
ereg ("([0-9]{4})([0-9]{2})([0-9]{2})", $then, $date_then);
$diff_years = $date_now[1] - $date_then[1];
$diff_months = $date_now[2] - $date_then[2];
if ($date_now[2] < $date_then[2]) {
$diff_years -= 1;
$diff_months = ($diff_months + 12) % 12;
}
$diff_months = ($diff_years * 12) + $diff_months;
return $diff_months;
}
?>
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