Find largest and second larges number in each row and column

Question

I am trying to find the largest and second largest number in each row and column. The largest numbers are easy, but how do I find the second largest?

After I found them I also want to calculate the difference of the two largest numbers in each row and column.

c = {{36, 32, 33, 19}, {10, 8, 7, 20}, {12, 17, 16, 29}, {23, 15, 16, 
    28}};
Max /@ c
Max /@ Transpose[c]

Answer 1

#[[Ordering[#, -2]]] & /@ c
#[[Ordering[#, -2]]] & /@ Transpose[c]

Answer 2

Use TakeLargest:

fn = TakeLargest[#, 2] &;

(* Largest in rows *)
fn /@ c

{{36, 33}, {20, 10}, {29, 17}, {28, 23}}

(*Largest in columns *)
fn /@ Transpose@c

{{36, 23}, {32, 17}, {33, 16}, {29, 28}}