=proto
void *duk_to_buffer(duk_context *ctx, int index, size_t *out_size);

=stack
[ ... val! ... ] -> [ ... buffer(val)! ... ]

=summary
<p>Replace the value at <code>index</code> with a buffer-coerced value.  Returns
a pointer to the buffer data (may be <code>NULL</code> for a zero-size buffer),
and writes the size of the buffer into <code>*out_size</code> (if <code>out_size</code>
is non-<code>NULL</code>).  If <code>index</code> is invalid, throws an error.</p>

<p>Coercion rules:</p>
<ul>
<li>Buffer: no change, dynamic/fixed nature not changed</li>
<li>String: coerces into a fixed size buffer, byte-for-byte</li>
<li>Other types: first apply Ecmascript
<a href="http://www.ecma-international.org/ecma-262/5.1/#sec-9.8">ToString()</a>,
then coerce into a fixed size buffer, byte-for-byte</li>
</ul>

=example
void *ptr;
size_t sz;

ptr = duk_to_buffer(ctx, -3, &sz);
printf("coerced data at %p, size %u\n", ptr, (unsigned int) sz);

=tags
stack
buffer