=proto
duk_c_function duk_require_c_function(duk_context *ctx, int index);

=stack
[ ... val! ... ]

=summary
<p>Like <code><a href="#duk_get_c_function">duk_get_c_function()</a></code>, but
throws an error if the value at <code>index</code> is not an Ecmascript function
associated with a Duktape/C function or if the index is invalid.</p>

=example
duk_c_function funcptr;

funcptr = duk_require_c_function(ctx, -3);

=tags
stack
function