Assume the existence of a class arr with two (public) data members: a pointer to integer named arr_ptr, and an integer variable namedlength that will contain the number of elements in the array. assume the variable a has been declared to be of type arr, an array has been allocated and assigned to arr_ptr, and length has been assigned the proper value (i. e., the number of elements in the array). write the code to add 1 to each element of the array.