The number of compound/s given below which contain/s $$-COOH$$ group is ______. (Integer answer)
(A) Sulphanilic acid (B) Picric acid (C) Aspirin (D) Ascorbic acid

We need to identify which of the given compounds contain a $$-COOH$$ (carboxyl) group.

(A) Sulphanilic acid: This is 4-aminobenzenesulfonic acid ($$H_2N\text{-}C_6H_4\text{-}SO_3H$$). It contains a sulfonic acid group ($$-SO_3H$$) and an amino group ($$-NH_2$$), but no $$-COOH$$ group.

(B) Picric acid: This is 2,4,6-trinitrophenol ($$C_6H_2(NO_2)_3OH$$). It is a phenol derivative with nitro groups. It does not contain a $$-COOH$$ group.

(C) Aspirin: This is acetylsalicylic acid ($$CH_3COOC_6H_4COOH$$). It contains a $$-COOH$$ group attached to the benzene ring, along with an ester group ($$-OCOCH_3$$). So aspirin does contain a $$-COOH$$ group.

(D) Ascorbic acid (Vitamin C): Despite being called an "acid," ascorbic acid does not contain a $$-COOH$$ group. It is a lactone (cyclic ester) with an enediol structure. Its acidity comes from the enol hydroxyl groups, not from a carboxyl group.

Therefore, only aspirin contains a $$-COOH$$ group, and the answer is $$\boxed{1}$$.