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Why do arrays start at 0?

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Re: Why do arrays start at 0?

#141

Post by bregma »

hougaard wrote: post #14

It really comes down to a choice between a machine-focused (0) or human-focused (1) approach. The 0 makes a lot of sense in a C pointer world where memcpy and other alike functions can be written very thight. The 1 makes a lot of sense in a human world, when we count, we start at 1, we talk about the "1st", counting on finger starts with 1, etc. I once were at a Lua (1 indexed language) conference where this was disc…

Ah, yes. Cardinal numbers and ordinal numbers both end in the word "numbers" so they're the same thing. No need to distinguish between having three apples and having the third apple.

Re: Why do arrays start at 0?

#142

Post by ncmncm »

The crucial fact is that if your language supports 0-indexing, you can do that if you like. OR, you can pretend it has 1-indexing, and do that instead.

If your language doesn't support zero-indexing, then you are stuck with 1-indexing, and that's that.

So, zero-indexing is the natural thing to put in a language, as it accommodates everybody.

Re: Why do arrays start at 0?

#143

Post by Old_Thrashbarg »

hougaard wrote: post #14

It really comes down to a choice between a machine-focused (0) or human-focused (1) approach. The 0 makes a lot of sense in a C pointer world where memcpy and other alike functions can be written very thight. The 1 makes a lot of sense in a human world, when we count, we start at 1, we talk about the "1st", counting on finger starts with 1, etc. I once were at a Lua (1 indexed language) conference where this was disc…

I believe there's a powerful status quo bias.

Doing the reversal test, if programming languages had all been 1-indexed, then I doubt we'd hear much from people, in 2022, saying "I think the first element should be 0, and the second 1".

Re: Why do arrays start at 0?

#144

Post by brobinson »

auggierose wrote: post #81
nsajko wrote: post #6

Earlier quoted context omitted.

No. 1. Optimizing compilers exist. 2. Addressing at fixed offsets is cheap (a single instruction): https://en.wikipedia.org/wiki/Addressing_mode 0-based indexing is superior (as a default) because it simplifies a lot of common math, as discussed in TFA.

TFA = Thanks For Asking?

The "Friendly" Article

Re: Why do arrays start at 0?

#145

Post by atwood22 »

kazinator wrote: post #55
atwood22 wrote: post #37

Earlier quoted context omitted.

No, we don't count from 0. That's like saying we start counting a baker's cup from 0 because you can have half a cup.

What do you do for a living, and why are they paying you not to understand this?

Do you know the definition of countable? A set S is countable if there is a one-to-one mapping from S to N where N is the natural numbers. Do you know that 0 is not a member of the natural numbers? We literally start counting at 1 by definition of countable.

Re: Why do arrays start at 0?

#146

Post by emaginniss »

atwood22 wrote: post #37
randomdata wrote: post #29

Earlier quoted context omitted.

The moment you are born you are 0 years old (or perhaps 0.75 years old, but we don't usually recognize that). We count from zero in this case, at least implicitly. In some cultures you are considered 1 the moment you are born, so the zero indexing isn't universal here, but typical in North America as noted earlier.

No, we don't count from 0. That's like saying we start counting a baker's cup from 0 because you can have half a cup.

Ok, use the baker and cup as an example. If you have an empty cup and put half of a cup of flour in it, you now have 0.5 cups of flour. Notice the zero before the ".5". That is us, normal humans, realizing that until you add enough to have 1 of something, you have between 0 and 0.999 repeating.

Re: Why do arrays start at 0?

#147

Post by yuliyp »

10000truths wrote: post #134
bluetomcat wrote: post #120

Earlier quoted context omitted.

A disadvantage comes to mind. While the following loop works as expected: for (size_t i = 0; i The following causes an unsigned integer underflow and is an infinite loop: for (size_t i = length - 1; i >= 0; i--) ...

for (size_t i = 0; i EDIT: change i to j

That's quite broken (you'd want a different variable inside the body, vs clobbering the iteration counter, else this would process the last item in your list, then exit).

Re: Why do arrays start at 0?

#148

Post by atwood22 »

kazinator wrote: post #58
atwood22 wrote: post #37

Earlier quoted context omitted.

No, we don't count from 0. That's like saying we start counting a baker's cup from 0 because you can have half a cup.

The counting activity doesn't begin when the first item is registered; it begins when the counter is initialized to zero. A decision is made to begin counting, along with the realization that nothing has been counting yet. That's when counting has started. When the first item is seen, the counting is then continuing. Suppose your job is to count some events. You check in for work at 8:00 a.m., but the first event has…

No, the mathematical definition of counting (i.e. whether or not a set is countable) involves mapping to the natural numbers, which doesn’t include 0.

Re: Why do arrays start at 0?

#149

Post by Old_Thrashbarg »

bregma wrote: post #141
hougaard wrote: post #14

It really comes down to a choice between a machine-focused (0) or human-focused (1) approach. The 0 makes a lot of sense in a C pointer world where memcpy and other alike functions can be written very thight. The 1 makes a lot of sense in a human world, when we count, we start at 1, we talk about the "1st", counting on finger starts with 1, etc. I once were at a Lua (1 indexed language) conference where this was disc…

Ah, yes. Cardinal numbers and ordinal numbers both end in the word "numbers" so they're the same thing. No need to distinguish between having three apples and having the third apple.

If you ask most people to just label their apples, they'd call the first one "1", and so on. Very few people would say, "please pass me apple #0".

Re: Why do arrays start at 0?

#150

Post by goatlover »

kazinator wrote: post #58
atwood22 wrote: post #37

Earlier quoted context omitted.

No, we don't count from 0. That's like saying we start counting a baker's cup from 0 because you can have half a cup.

The counting activity doesn't begin when the first item is registered; it begins when the counter is initialized to zero. A decision is made to begin counting, along with the realization that nothing has been counting yet. That's when counting has started. When the first item is seen, the counting is then continuing. Suppose your job is to count some events. You check in for work at 8:00 a.m., but the first event has…

What counter? You're saying a counter exists before people start counting? Is this a form of mathematical Platonism?
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