Why does the indexing start with zero in 'C'?

Question

Why does the indexing in an array start with zero in C and not with 1?

Answer 1

Because 0 is how far from the pointer to the head of the array to the array's first element.

Consider:

int foo[5] = {1,2,3,4,5};

To access 0 we do:

foo[0] 

But foo decomposes to a pointer, and the above access has analogous pointer arithmetic way of accessing it

*(foo + 0)

These days pointer arithmetic isn't used as frequently. Way back when though, it was a convenient way to take an address and move X "ints" away from that starting point. Of course if you wanted to just stay where you are, you just add 0!