Cursor within cursor to compare same column's record not executing

Question

I am working on small PL/SQL program which compare the column record with itself using cursor. When I execute the code it takes long time seems like falling in endless loop.

Table Data :-

STD
----
 2
 1
 4
 3
 6
 5
 8
 7
 10
 9
 12
 11

below is my code:-

declare 
s number;
s1 number;
c number := 0;
cursor c1 is (select std from data);
cursor c2 is (select std from data);
begin
open c1;
loop
    fetch c1 into s;
     open c2;
        loop
            fetch c2 into s1;
            if s < s1
            then    
                c := c + 1;
           end if;
        end loop;
     insert into con values(c);
     close c2;       
end loop;
close c1; 
end;
/

Expected result :-

C=10
C=10
C=8
C=8
C=6
C=6
C=4
C=4
C=2
C=2
C=0
C=null

Answer 1

You should add

EXIT WHEN c1%NOTFOUND;

EXIT WHEN c2%NOTFOUND;

after corresponding fetch. e.g.

declare 
s number;
s1 number;
c number := 0;
cursor c1 is (select std from data);
cursor c2 is (select std from data);
begin
open c1;
loop
    fetch c1 into s;
    EXIT WHEN c1%NOTFOUND;
     open c2;
        loop
            fetch c2 into s1;
            EXIT WHEN c2%NOTFOUND;
            if s < s1
            then    
                c := c + 1;
           end if;
        end loop;
     insert into con values(c);
     close c2;       
end loop;
close c1; 
end;
/