Retrieve Indices of Associative Array as Collection In PL/SQL, suppose I have some associative array defined as follows:

declare 
       type a_arr_t is table of PLS_INTEGER index by PLS_INTEGER;
       a_arr a_arr_t;


I then, sparsely, populate the array as follows:

begin
      a_arr(1)   := 2;
      a_arr(10)  := 4;
      a_arr(100) := 6;
end;


Is there some operator or function that can give me the indices of the array, (1,10,100) as a collection of some sort, something like indices of in a forall statement?
Is there some operator or function that can give me the indices of the array


No, you have to loop through the associative array:

declare 
       type a_arr_t is table of PLS_INTEGER index by PLS_INTEGER;
       type keys_t is table of PLS_INTEGER;
       a_arr a_arr_t;
       keys_ keys_t := keys_t();
       l_index integer;
begin
      a_arr(1)   := 2;
      a_arr(10)  := 4;
      a_arr(100) := 6;

      l_index := a_arr.first;
      while (l_index is not null)
      loop
          keys_.extend();
          keys_(keys_.count):=l_index;
          dbms_output.put_line(keys_(keys_.count));
          l_index := a_arr.next(l_index);
      end loop;
end;
/

/*
1
10
100
*/