?</tt> instead of the number of elements, e.g. <tt>"int[?]"</tt>.
The number of elements (<tt>nelem</tt>) must be given when it's
<a href="#ffi_new">created</a>.</li>
<li><b>VLS</b> &mdash; A variable-length struct is a <tt>struct</tt> C
type where the last element is a <b>VLA</b>. The same rules for
declaration and creation apply.</li>
</ul>

<h2 id="decl">Declaring and Accessing External Symbols</h2>
<p>
External symbols must be declared first and can then be accessed by
indexing a <a href="ext_ffi_semant