wn. E.g. when the length is returned by a C&nbsp;call like
<tt>sprintf()</tt>.
</p>

<h3 id="ffi_copy"><tt>ffi.copy(dst, src, len)<br>
ffi.copy(dst, str)</tt></h3>
<p>
Copies the data pointed to by <tt>src</tt> to <tt>dst</tt>.
<tt>dst</tt> is converted to a <tt>"void&nbsp;*"</tt> and <tt>src</tt>
is converted to a <tt>"const void&nbsp;*"</tt>.
</p>
<p>
In the first syntax, <tt>len</tt> gives the number of bytes to copy.
Caveat: if <tt>src</tt> is a Lua string, then <tt>len</tt> must not
exceed <tt>#src+1</