c : The variables arr1 and arr2 have been declared as pointers to integers . An array of 10 elements has been allocated, its pointer assigned to arr1, and the elements initialized to some values . Allocate an array of 20 elements , assign its pointer to arr2, copy the 10 elements from arr1 to the first 10 elements of arr2, and initialize the remainder of the elements of arr2 to 0.

C - Pointer to Pointer (Double Pointer) - GeeksforGeeks