Calculating start and end dates of a week.

"How do I calculate start (monday) and end (sunday) dates from a given week number for a specified year?" Instead of having to come up with your own algorithm you can simply do the following in PHP 5.1 and higher:

<?php
// Monday
echo date(
    datetime::ISO8601,
    strtotime("2006W37"));

// Sunday
echo date(
    datetime::ISO8601,
    strtotime("2006W377"));
?>

The format is " year 'W' weeknr ( daynr )?" where the default daynr is 1 being the Monday of that week. The daynr can be in the range 0 to 7. The weeknr is the ISO week number . Please note that the " year '-W' weeknr ( '-' daynr )?" format is only supported in PHP 5.2 and higher.