How to determine number of rows in a table

I have searched many places, but were unable to find a solution. I wanted to have a way to find out the number of table rows after a Ajax call.

I see the followings in some posts

oTable.fnSettings().fnRecordsTotal()
oTable.fnGetData().length

but, they did not seem to work. Not sure if they are obsolete or not (i.e Hungarian notation).

If I have

var table = $(#example).dataTable();

alert(table.fnGetData().length) does not seem to work. I am using the datatables 1.10.1.

Thanks, Alex