SQL & PL/SQL :: Concatenation On Columns

I have problem with query ( i'll only use DUAL table for example):

SELECT T.DUMMY P1,
T.DUMMY P2,
T.DUMMY C1,
T.DUMMY C2,
T.DUMMY C3,
T.DUMMY C4,
T.DUMMY C5
FROM DUAL T;

I need to concatenate only columns with name starting with C and add separator between them. Is there any function do concatenate columns using separator like:

SELECT T.DUMMY P1,
T.DUMMY P2,
DBMS_SOMETHING.SOME_FUNCTION(',', C1,C2,C3,C4,C5)
FROM DUAL T;

Or I must do like this:

SELECT T.DUMMY P1,
T.DUMMY P2,
C1 || ',' || C2 || ',' || C3 || ',' || C4 || ',' || C5
FROM DUAL T;

problem is that I have 3.000+ columns in 23 different selects :/