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Why do arrays start at 0?

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Re: Why do arrays start at 0?

#71

Post by kazinator »

numlock86 wrote: post #35
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…

> It really comes down to a choice between a machine-focused (0) or human-focused (1) approach. Just think of 0-based as offset-based and 1-based as index-based. Both are intuitive just like that. I never get why people arguing over this bring pointers and memory (or anything computer related) to the table. No normal person is going to understand that, but everyone understands that if you don't move at all (0 offset)…

Offset-based lets you refer to an abstract location that is after the last element without resorting to n + 1.

  [ ] [ ] [ ] ...    [ ]
 0   1   2   3   n-1     n
We can regard this n as a "virtual zero", and then make it possible to index the n - 1 element also indexable as just -1. The index -n then aliases to 0.

Re: Why do arrays start at 0?

#72

Post by auggierose »

Funny, just a few hours ago I asked myself the related question "Should indices start with 0 or 1?" (not for the first time). I pretty much switch my opinion as many times as I think about it.

Here is a nice discussion on stackoverflow https://cseducators.stackexchange.com/questions/5023/why-do-...

The first answer nicely retells the dijkstra argument: integer ranges should be described using half open intervals, and [n, m) is nicer than (n, m]. Furthermore, [0, n) is nicer than [1, n+1), and that's that.

The second answer makes the observation that there is a difference between indexing and counting, and that even in daily life often the first element is indexed by 0.

Still, I rather like indexing the first element of a sequence with 1.

Re: Why do arrays start at 0?

#73

Post by unnouinceput »

User23 wrote: post #3

Pascal's arrays start at 1, at least by default.

This is false. Pascal arrays start at whatever you want. As for what is happening behind closed doors (aka linker), those start at zero, but with an offset kept separately (that's why C blew out of the water Pascal in terms of speed when looping through an array). And in Pascal you cannot create a dynamic array with anything other than 0-based.

You are confusing arrays with strings. Those used to start at 1, but since Unicode took over (~2007) strings are implemented as zero-based too (even though you can still think of them as 1-based when writing code).

Also in Delphi, when creating a cross-platform application, strings are treated as 0-based, with even multiple locations in documentation stressing this importance due to having enough differences between classic VCL and the new kid on the block (aka FireMonkey).

Re: Why do arrays start at 0?

#74

Post by kazinator »

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…

In Western music theory, intervals are one based. No pitch change is "unison"; one diatonic step is a "major second" and so on. As a result of this silly state of affairs, an octave occurs every 7 notes, even though the root "oct" means eight. Furthermore, a "rule of nines" is needed to invert an interval: e.g. inversion of minor 3rd is a major 6th (exchange major/minor, subtract from 9).

Re: Why do arrays start at 0?

#75

Post by espadrine »

t_mann wrote: post #56
ethbr0 wrote: post #53

Earlier quoted context omitted.

Does Europe has a zero floor? Please tell me Europe zero-indexes their stories!

They do, it's called the ground floor.

In France, it is called the rez-de-chaussée. The “premier étage” (literally translated as “first floor”) is what the US calls the second floor.

Re: Why do arrays start at 0?

#76

Post by atwood22 »

randomdata wrote: post #50
atwood22 wrote: post #46

Earlier quoted context omitted.

No, it just means we have a different notion of what a year is in regards to age. Similar to how different cultures can use different units of measurement for length, mass, etc.

Yes, exactly. One of which carries an implicit zero indexing. The date of birth doesn't disappear just because you decided to use a different measuring device.

No, it doesn’t carry an implicit 0 index. Measuring age (in the West) is like measuring distance. You start at 0, but that doesn’t mean the first item is at index 0.

Re: Why do arrays start at 0?

#77

Post by dang »

The article this one points to has had a few threads:

The origin of zero-based array indexing - https://news.ycombinator.com/item?id=6879478 - Dec 2013 (107 comments)

Zero-based arrays and the mythology of programming - https://news.ycombinator.com/item?id=6708409 - Nov 2013 (1 comment)

Citation Needed - https://news.ycombinator.com/item?id=6595521 - Oct 2013 (2 comments)

Threads about the EWD mentioned by jaapsen01:

Why numbering should start at zero (1982) - https://news.ycombinator.com/item?id=22162705 - Jan 2020 (220 comments)

Dijkstra's argument on why numbering should start at zero [pdf] - https://news.ycombinator.com/item?id=17850441 - Aug 2018 (1 comment)

Why numbering should start at zero (1982) - https://news.ycombinator.com/item?id=17765034 - Aug 2018 (63 comments)

Why numbering should start at zero (1982) - https://news.ycombinator.com/item?id=13186225 - Dec 2016 (216 comments)

Why numbering should start at zero (1982) - https://news.ycombinator.com/item?id=9761355 - June 2015 (47 comments)

Dijkstra: Why numbering should start at zero - https://news.ycombinator.com/item?id=777580 - Aug 2009 (71 comments)

Also these. Others? I'm a little surprised there aren't more.

Why do we count starting from zero? - https://news.ycombinator.com/item?id=17923391 - Sept 2018 (1 comment)

Why C Arrays Start at Zero: I Don't Know - https://news.ycombinator.com/item?id=11228267 - March 2016 (3 comments)

Why C Arrays Start at Zero: I Don't Know - https://news.ycombinator.com/item?id=11114704 - Feb 2016 (2 comments)

Re: Why do arrays start at 0?

#79

Post by [deleted] »

numlock86 wrote: post #35
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…

> It really comes down to a choice between a machine-focused (0) or human-focused (1) approach. Just think of 0-based as offset-based and 1-based as index-based. Both are intuitive just like that. I never get why people arguing over this bring pointers and memory (or anything computer related) to the table. No normal person is going to understand that, but everyone understands that if you don't move at all (0 offset)…

[deleted]

Re: Why do arrays start at 0?

#80

Post by zajio1am »

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…

> 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.

It is more like counting from 1 is just a leftover from times where zero was not commonly considered as number. Once one have zero, it makes sense to use it as an initial ordinal (see e.g. set theory, where zero is both initial ordinal and initial cardinal number, way before computers).

Another example is time and date, we start counting of days from 1, but counting of hours (at least in 24-hour notation) and minutes from 0.

> Luis started explaining why Lua was 1-index with this sentence: "The 1st argument ...."

Note that for spoken language, it is "The first argument ..." and 'first' is etymologically unrelated to 'one', but related to 'foremost', 'front', so it make sense to use 'first' for the initial item in the sequence even when using counting from 0.

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