rubah variable di php

yg ini? <pre> $tgl_p2 = date("d-m-Y",strtotime('-2 month',strtotime($tanggal_expired))); </pre>

formatnya (tanggal-bulan-tahun) : 28-06-2018 tapi karena input type agan type='date' pasti g muncul.

coba ubah jadi gini :

<pre> &lt;?php include 'class/reminder.php'; $reminder = new reminder(); ?&gt; &lt;?php $result = $reminder-&gt;getData(); $data = $result-&gt;fetch_assoc(); $tanggal_expired = $data['tanggal_expired']; $tgl_p2 = date("Y-m-d",strtotime('-2 month',strtotime($tanggal_expired))); $tindak_lanjut = date("Y-m-d",strtotime('+1 month',strtotime($tgl_p2))); ?&gt; &lt;html&gt; &lt;head&gt; &lt;title&gt;reminder&lt;/title&gt; &lt;/head&gt; &lt;body&gt; &lt;center&gt;&lt;h1&gt;Program Percobaan. Semoga Berhasil.&lt;/h1&gt; &lt;a href=""&gt;&lt;/a&gt; &lt;form method="POST" action="controllers/reminder/create.php"&gt; &lt;input type="hidden" value="" name="id"&gt; &lt;input type="date" name="tanggal_expired" value="&lt;?php echo $tanggal_expired; ?&gt;"&gt;&lt;/br&gt; &lt;input type="date" name="tgl_p2" value="&lt;?php echo $tgl_p2; ?&gt;" &gt;&lt;/br&gt; &lt;br&gt;&lt;br&gt; &lt;input type="submit" value="submit"&gt; &lt;/form&gt; &lt;h1&gt;&copy Development 2018&lt;/h1&gt; &lt;/center&gt; &lt;/body&gt; &lt;/html&gt; </pre>