php variables comparison == vs ===
<p>this is code:</p>

<pre><code>$s = 0;
$d = "dd";

if ($s == $d) {
    var_dump($s);
    die(var_dump($d));
}
</code></pre>

<p>result is:</p>

<pre><code>int 0

string 'dd' (length=2)
</code></pre>

<p>Please explain why.</p>

<p>why <code>($s == $d)</code> results as true?</p>

<p>Of course, if <code>===</code> is used it will results as false but why this situation requires <code>===</code>?
Shouldn't it be returned false in both situations?</p>
