next(table [, index])

next returns the next index of the table and its associated value. When called with null as its second argument, next returns an initial index and its associated value. When called with the last index, or with null in an empty table, next returns null. If the second argument is absent, then it is interpreted as null. In particular, you can use next(t) to check whether a table is empty.

The order in which the indices are enumerated is not specified, even for numeric indices. (To traverse a table in numeric order, use a numerical for or the ipairs function.)

The behavior of next is undefined if, during the traversal, you assign any value to a non-existent field in the table. You may however modify existing fields. In particular, you may clear existing fields.