On Saturday, 1 August 2015 at 17:55:06 UTC, John Colvin wrote:
On Saturday, 1 August 2015 at 09:35:53 UTC, DLearner wrote:
Does the D language set in stone that the first element of an
array _has_ to be index zero?
For the builtin slice types? Yes, set in stone.
Wouldn't starting array elements at one avoid the common
'off-by-one' logic error, it does
seem more natural to begin a count at 1.
Actually, maybe even better to allow array definitions of form
int foo[x:y];
(y >= x) creating integer variables foo[x],
foo[x+1],...,foo[y].
I think the (very old) IBM PL/I language was like this.
See
https://www.cs.utexas.edu/users/EWD/transcriptions/EWD08xx/EWD831.html
As other commenters have/will point out, you can easily define
a custom type in D that behaves as you describe, and - Dijkstra
notwithstanding - there are valid uses for such things.
D is a C derivative, so it seems a shame not to identify causes
of bugs in C,
and design them out in D.
For example, in C difficult to write non-trivial commercial
programs without using pointers.
Pointer manipulation has a terrible reputation for bugs.
But in D, easy to write commercial programs without using
pointers.
Problem has been designed away.
Similarly, off-by-one array bugs are commonplace in C.
We should seek to eliminate the source of those bugs, which
basically reduces to the
issue that programmers find it unnatural to start a count at zero.
Whether they _should_ find a zero start unnatural is irrelevant -
they just do as an
observed fact, so let's change the language so the issue is
avoided (designed away).
Suggestion: if the codebase for D is considered so large that
zero-basing cannot now be changed,
why not extend the language to allow for array definitions like
'int[x:y] foo'?
And then have a rule that 'int[:y] bar' defines a 1-based array
of y elements?
