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Python "why" questions

Steven D'Aprano steve at REMOVE-THIS-cybersource.com.au
Sat Aug 7 09:38:20 EDT 2010 
On Sat, 07 Aug 2010 14:00:59 +0200, Thomas Jollans wrote:

> On 08/07/2010 05:05 AM, Default User wrote:
>>>From "the emperor's new clothes" department:
>> 
>> 1)  Why do Python lists start with element [0], instead of element [1]?
>> "Common sense" would seem to suggest that lists should start with [1].
> 
> As others have pointed out, there is a nice argument to be made for
> zero-based indices. However, the killer reason is: "it's what everybody
> else does." 

I'll have you know that there are still some Pascal programmers in the 
world, thank you.



> As it stands, the only perceived problem with zero-based
> indices is that it's one of the many tiny confusions that new
> programmers face. On the other hand, it's the way nearly every other
> popular programming language does it, and therefore, it's the way almost
> every programmer likes to think about sequences.

It didn't take me long to get used to thinking in zero-based indexes, but 
years later, I still find it hard to *talk* in zero-based indexes. It's 
bad enough saying that the first element in a list in the zeroth element, 
but that the second element is the first makes my head explode... 


> Also, it has the nice property that, for an infinite sequence, every
> integer makes sense as an index (in Python).

Er, what's the -1th element of an infinite sequence?



-- 
Steven
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