in *(cstr1+y)
here the adress is incremented by the value of y (i.e 1,2,3,4) and the memory location in the adress is displayed
but in (*cstr1)++
here the adress is incremented by the value of y (i.e 1,1,1,1) and the memory location in the adress is displayed
so there is a change in adress location that why so confusing..................