php function to get dates of last 7 weeks - php

Question

I am trying to build a php function that would return an array with the start date and end date of the last n number of weeks. this would include the current week. It would look something like this:
function lastnweeks(n)
{
//the code. I am not asking for the code itself but ideas on how to accomplish this
return $array;
}
$lastnweeks =lastnweeks(2);
print_r($lastnweeks);
this would print:
Array (
[0] => Array (
[0] => 2010/09/20
[1] => 2010/09/26
)[1] => Array (
[0] => 2010/09/13
[1] => 2010/09/19
))

Answer 1

I wouldn't use an absolute number of seconds because of daylight savings time and leapyears/leapseconds. You can let PHP's strtotime() function take care of this for you by using relative dates. Each iteration through a loop you can simply tell the function to find "Last Monday", and then use that result as your starting point for the next iteration.
The code:
$past_weeks = 7;
$relative_time = time();
$weeks = array();
for($week_count=0;$week_count<$past_weeks;$week_count++) {
$monday = strtotime("last Monday", $relative_time);
$sunday = strtotime("Sunday", $monday);
$weeks[] = array(
date("Y-m-d", $monday),
date("Y-m-d", $sunday),
);
$relative_time = $monday;
}
var_dump($weeks);
The output:
array
0 =>
array
0 => string '2010-09-20' (length=10)
1 => string '2010-09-26' (length=10)
1 =>
array
0 => string '2010-09-13' (length=10)
1 => string '2010-09-19' (length=10)
2 =>
array
0 => string '2010-09-06' (length=10)
1 => string '2010-09-12' (length=10)
3 =>
array
0 => string '2010-08-30' (length=10)
1 => string '2010-09-05' (length=10)
4 =>
array
0 => string '2010-08-23' (length=10)
1 => string '2010-08-29' (length=10)
5 =>
array
0 => string '2010-08-16' (length=10)
1 => string '2010-08-22' (length=10)
6 =>
array
0 => string '2010-08-09' (length=10)
1 => string '2010-08-15' (length=10)

Answer 2

Use strtotime to get the monday and then subtract the number of seconds for each week:
function lastnweeks($n) {
$time = strtotime('Monday 00:00:00+0000');
$arr = array();
while ($n-- > 0) {
$arr[] = array_reverse(array(
date('Y/m/d', $time-=86400), // sunday
date('Y/m/d', $time-=6*86400) // monday
));
}
return $arr;
}
array_reverse is used to reverse the array as the calculation walks backwards.

Answer 3

Take your pick
$last_week = strtotime('last Week');
echo "Last Week ".date("Y/m/d", $last_week)."<br />\n";
or
$last_week = mktime(0,0,0,date("m"),date("d")-7,date("Y"));
echo "Last Week ".date("Y/m/d", $last_week)."<br />\n";