how this works

Question

In this ' i ' array is not decalared
https://code.sololearn.com/clQIE7mWkwdE/?ref=app

Answer 1

a[i] is the same as *( a + i )
i[a] simply swaps the lhs and rhs: *( i + a )
since the + operator is commutative it doesn't matter on which side the operands are, the result is the same either way.