[drbaba]

> Computing the bounded index from an arbitrary index is simply i % c with zero based indexing, but becomes (i-1) % c + 1 with one based indexing.

Arguably, this is because the common definition of modular arithmetic is itself zero-based: “modulo N” maps all integers into the numbers [0,N-1]. It is fully possible to define a “%” operator that instead mapped the integers into the range [1,N], which might be more natural in 1-based languages?

[magila]

Great, now you've messed up all the other math that uses the modulo operator. The mathematical operators behave the way they do for well established reasons that long predate the invention of computers. It's going to be a tough sell to get everyone to adopt a wholesale refactoring of modulo arithmetic (and likely number theory in general) just for the "convenience" of one based indexing.