CODEWITHSUNDEEP
phpdateloopsstrtotimemktime
orhan bengisu
orhan bengisu

Reputation: 29

Strange problem while adding years to date in a loop

$start_date = strtotime('2011-08-21');

    for($i=0 ; $i < 5; $i++)
    {
        echo "i = $i  and ";

        $start_date = mktime(0, 0, 0, date("m", $start_date), date("d", $start_date), date("Y", $start_date)+$i);
        echo date('Y-m-d',$start_date)."<br /><hr />";
    }

i = 0 and 2011-08-21
i = 1 and 2012-08-21
i = 2 and 2014-08-21
i = 3 and 2017-08-21
i = 4 and 2021-08-21

i didn't understand why after 2012 it doesn't add correctly.

Thanks

Upvotes: 0

Views: 298

Answers (3)

Boris
Boris

Reputation: 749

Maybe you should do it like this if you want to add one year each time.

for($i=0 ; $i < 5; $i++)
{ echo "i = $i  and ";
  if($i>0)  $start_date = mktime(0, 0, 0, date("m", $start_date), date("d", $start_date), date("Y", $start_date)+1);
  echo date('Y-m-d',$start_date)."<br /><hr />";
}

Upvotes: 2

adlawson
adlawson

Reputation: 6431

It is working correctly. You're adding an incrementing number to the year on each iteration.

i = 0 and 2011-08-21 // 2011 + 0
i = 1 and 2012-08-21 // 2011 + 1
i = 2 and 2014-08-21 // 2012 + 2
i = 3 and 2017-08-21 // 2014 + 3
i = 4 and 2021-08-21 // 2017 + 4

You should either

  • +1 instead of +$1 to the year on each iteration
  • OR don't overwrite $start_date on each iteration

Update (without overwriting)

for($i=0 ; $i < 5; $i++)
{
    echo "i = $i  and ";

    // $new_date holds the updated date without overwriting
    $new_date = mktime(0, 0, 0, date("m", $start_date), date("d", $start_date), date("Y", $start_date)+$i);

    echo date('Y-m-d', $new_date)."<br /><hr />";
}

Upvotes: 2

Brett Walker
Brett Walker

Reputation: 3586

The following line

$start_date = mktime(0, 0, 0, date("m", $start_date), date("d", $start_date), date("Y", $start_date)+$i);

Should be

$start_date = mktime(0, 0, 0, date("m", $start_date), date("d", $start_date), date("Y", $start_date)+1);

Otherwise the year of the date is being increased by 1 then 2 then 3 the 4, as teh start date is being modified each time.

Upvotes: 1

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