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<h5 class="subsubsection">3.2.4.4 Freeing Objects in an Obstack</h5>

<p><a name="index-freeing-_0028obstacks_0029-311"></a>
To free an object allocated in an obstack, use the function
<code>obstack_free</code>.  Since the obstack is a stack of objects, freeing
one object automatically frees all other objects allocated more recently
in the same obstack.

<!-- obstack.h -->
<!-- GNU -->
<div class="defun">
&mdash; Function: void <b>obstack_free</b> (<var>struct obstack *obstack-ptr, void *object</var>)<var><a name="index-obstack_005ffree-312"></a></var><br>
<blockquote><p>If <var>object</var> is a null pointer, everything allocated in the obstack
is freed.  Otherwise, <var>object</var> must be the address of an object
allocated in the obstack.  Then <var>object</var> is freed, along with
everything allocated in <var>obstack</var> since <var>object</var>. 
</p></blockquote></div>

   <p>Note that if <var>object</var> is a null pointer, the result is an
uninitialized obstack.  To free all memory in an obstack but leave it
valid for further allocation, call <code>obstack_free</code> with the address
of the first object allocated on the obstack:

<pre class="smallexample">     obstack_free (obstack_ptr, first_object_allocated_ptr);
</pre>
   <p>Recall that the objects in an obstack are grouped into chunks.  When all
the objects in a chunk become free, the obstack library automatically
frees the chunk (see <a href="Preparing-for-Obstacks.html#Preparing-for-Obstacks">Preparing for Obstacks</a>).  Then other
obstacks, or non-obstack allocation, can reuse the space of the chunk.

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