c - Accessing 2D array elements using double pointer -

recently had interview in c. interviewer has asked me explain how access particular element in 2d array using double pointer. gave answer *(*(a+i)+j), a double pointer, i number of rows , j number of columns. later asked me explain using example. confused @ *(a+i) gives value instead of address , adding j gives junk value. can please explain.

remember in 1d array a[i] equals *(a+i). , there no 2d arrays in c, arrays of arrays.

so a[i][j] equal *(*(a+i)+j).

if type of a int**, type of (a+i) still int**, need dereference it. type of *(a+i) int* , type of *(*(a+i)+j) int.

about interview question, no matter a double pointer, should still use [] notation. alternative cumbersome:

int **a = ...; int x = a[i][j];