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o1 === o2 : FALSE
o1 !== o2 : TRUE
</pre></div>
    </pre></div>
   </div>   
   Which is the output we will expect to obtain given the comparison rules
   above. Only instances with the same values for their attributes 
   and from the same class are considered equal and identical.
  </p>
  <p class="para">
   Even in the cases where we have object composition, the same comparison
   rules apply. In the example below we create a container class that stores
   an associative array of <b class="classname">Flag</b> objects.
   <div class="example">
    <p><b>Example #2 Compound object comparisons in PHP 4</b></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /></span><span style="color: #007700">class&nbsp;</span><span style="color: #0000BB">FlagSet&nbsp;</span><span style="color: #007700">{<br />&nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;</span><span style="color: #0000BB">$set</span><span style="color: #007700">;<br /><br />&nbsp;&nbsp;&nbsp;&nbsp;function&nbsp;</span><span style="color: #0000BB">FlagSet</span><span style="color: #007700">(</span><span style="color: #0000BB">$flagArr&nbsp;</span><span style="color: #007700">=&nbsp;array())&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">$this</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">set&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">$flagArr</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;}<br /><br />&nbsp;&nbsp;&nbsp;&nbsp;function&nbsp;</span><span style="color: #0000BB">addFlag</span><span style="color: #007700">(</span><span style="color: #0000BB">$name</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$flag</span><span style="color: #007700">)&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">$this</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">set</span><span style="color: #007700">[</span><span style="color: #0000BB">$name</span><span style="color: #007700">]&nbsp;=&nbsp;</span><span style="color: #0000BB">$flag</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;}<br /><br />&nbsp;&nbsp;&nbsp;&nbsp;function&nbsp;</span><span style="color: #0000BB">removeFlag</span><span style="color: #007700">(</span><span style="color: #0000BB">$name</span><span style="color: #007700">)&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp;(</span><span style="color: #0000BB">array_key_exists</span><span style="color: #007700">(</span><span style="color: #0000BB">$name</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$this</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">set</span><span style="color: #007700">))&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;unset(</span><span style="color: #0000BB">$this</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">set</span><span style="color: #007700">[</span><span style="color: #0000BB">$name</span><span style="color: #007700">]);<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}<br />&nbsp;&nbsp;&nbsp;&nbsp;}<br />}<br /><br /><br /></span><span style="color: #0000BB">$u&nbsp;</span><span style="color: #007700">=&nbsp;new&nbsp;</span><span style="color: #0000BB">FlagSet</span><span style="color: #007700">();<br /></span><span style="color: #0000BB">$u</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">addFlag</span><span style="color: #007700">(</span><span style="color: #DD0000">'flag1'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$o</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$u</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">addFlag</span><span style="color: #007700">(</span><span style="color: #DD0000">'flag2'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$p</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$v&nbsp;</span><span style="color: #007700">=&nbsp;new&nbsp;</span><span style="color: #0000BB">FlagSet</span><span style="color: #007700">(array(</span><span style="color: #DD0000">'flag1'</span><span style="color: #007700">=&gt;</span><span style="color: #0000BB">$q</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'flag2'</span><span style="color: #007700">=&gt;</span><span style="color: #0000BB">$p</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">$w&nbsp;</span><span style="color: #007700">=&nbsp;new&nbsp;</span><span style="color: #0000BB">FlagSet</span><span style="color: #007700">(array(</span><span style="color: #DD0000">'flag1'</span><span style="color: #007700">=&gt;</span><span style="color: #0000BB">$q</span><span style="color: #007700">));<br /><br />echo&nbsp;</span><span style="color: #DD0000">"\nComposite&nbsp;objects&nbsp;u(o,p)&nbsp;and&nbsp;v(q,p)\n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">compareObjects</span><span style="color: #007700">(</span><span style="color: #0000BB">$u</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$v</span><span style="color: #007700">);<br /><br />echo&nbsp;</span><span style="color: #DD0000">"\nu(o,p)&nbsp;and&nbsp;w(q)\n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">compareObjects</span><span style="color: #007700">(</span><span style="color: #0000BB">$u</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$w</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

    <div class="example-contents"><p>The above example will output:</p></div>
    <div class="example-contents"><pre>
<div class="cdata"><pre>
Composite objects u(o,p) and v(q,p)
o1 == o2 : TRUE
o1 != o2 : FALSE
o1 === o2 : TRUE
o1 !== o2 : FALSE

u(o,p) and w(q)
o1 == o2 : FALSE
o1 != o2 : TRUE
o1 === o2 : FALSE
o1 !== o2 : TRUE
</pre></div>
    </pre></div>
   </div>
  </p>
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