Is there a C API equivalent to the new # operator for tables?

["Ram Firestone" <bichir@...>]

I think the title says it all, but just to make sure I would like to know if there is a C API function (or another easy way) to get
the length of a table that is being used as an array. Indexing will start at one and there will be no holes. I didn't see anything
in the documentation but I wanted to make sure I didn't miss anything. I am looking for a method that is reasonably fast.