As Joel points out in Stack Overflow podcast #34, in C Programming Language (aka: K & R), there is mention of this property of arrays in C:
a == 5[a]
Joel says that it’s because of pointer arithmetic but I still don’t understand. Why does
a == 5[a]?
The C standard defines the
 operator as follows:
a[b] == *(a + b)
a will evaluate to:
*(a + 5)
5[a] will evaluate to:
*(5 + a)
a is a pointer to the first element of the array.
a is the value that’s 5 elements further from
a, which is the same as
*(a + 5), and from elementary school math we know those are equal (addition is commutative).