I think an age-based way to phrase it: in your 1st year, your age is 0; in your 2nd year, your age is 1; and so on. We can assign people numbers indicating what year of their lives they're in, or how many years they have lived, and both are fine, but we've settled on the latter.
That's not an argument. It's a coincidence. There are applications where what you care about is the number of predecessors (indeed, that's what the compiler cares about, which is why we have 0-indexing in the first place), but they are a tiny minority of all indexing.
> I think an age-based way to phrase it: in your 1st year, your age is 0; in your 2nd year, your age is 1; and so on.
But that isn't even true. No one ever reports the age of their new child as 0; instead, they will report a positive number of months, or -- if it's an extremely new child -- of weeks or days.
> That's not an argument. It's a coincidence. There are applications where what you care about is the number of predecessors (indeed, that's what the compiler cares about, which is why we have 0-indexing in the first place), but they are a tiny minority of all indexing.
I think there's nothing to say to the first two sentences but that I regard it as an argument that may be more or less convincing. I don't know exactly what it means for something to be an argument vs. a coincidence; it is a coincidence that, say, my name is what it is, but it is nonetheless correct for me to argue that that is my name.
These are all conventions anyway, and there is not much use (or even meaning) in arguing about which one is the right or wrong convention, just which one makes more or less sense; and this is one way to make sense of 0-based indexing, though of course there are also ways to make sense of 1-based indexing.
I'm not sure I buy that these cases are a tiny minority, but I'm certainly in no position to produce any data to the contrary.
> > I think an age-based way to phrase it: in your 1st year, your age is 0; in your 2nd year, your age is 1; and so on.
> But that isn't even true. No one ever reports the age of their new child as 0; instead, they will report a positive number of months, or -- if it's an extremely new child -- of weeks or days.
I can believe that ages aren't reported that way, although I think that a child who will be 1 year in 1 year should logically be said to be 0 years; but we can avoid that debate by considering future years: in, to pick the example that applies to me, my 42nd year of life, I am 41 (I could say 41 and 1 month, but I don't—in fact, there's a Seinfeld joke about that). Similarly, the 42nd entry in a 0-indexed array is indexed 41. It doesn't have to be that way, but I don't think one can argue that there's anything logically amiss about it (nor about 1-based indexing … but we do have to pick one).
> I think there's nothing to say to the first two sentences but that I regard it as an argument that may be more or less convincing. I don't know exactly what it means for something to be an argument vs. a coincidence; it is a coincidence that, say, my name is what it is, but it is nonetheless correct for me to argue that that is my name.
Sure. But we're talking about whether to index arrays from 0 or 1. It is true that naming an array element after the quantity of its predecessors will tell you the number of predecessors the element has. But that's not an argument for why you should do it; there would need to be some kind of benefit to having that information. Without a benefit, it's just something that happens to be true.
That's the difference between an argument and a coincidence.
I think an age-based way to phrase it: in your 1st year, your age is 0; in your 2nd year, your age is 1; and so on. We can assign people numbers indicating what year of their lives they're in, or how many years they have lived, and both are fine, but we've settled on the latter.