The first p = 1
p = a + 1, *p = 2
p = a + 2, *p = 3
p = a + 3, *p = 4
p = a + 4, *p = 5
The value of a = 1 2 3 4 5
Update the items...
The value of a = 0 10 20 30 40
2[a] = 20 (the same as a[2] = 20)
