access to the keys of a table

[Gabriel Peyré <nikopol0@...>]

Sorry if this question has already been answered, I didn't manage to find a
simple answer (both on the archives and in
the refman).

I want to access the different elements of a table through the API (i.e.
code is written in C) without knowing
their keys. The only possibility I see is to access the table as a simple C
array using lua_rawgeti.
Is their a way to access the key associated with the ith element (not only
the value) ?

Thanks in advance.

Gabriel Peyré