Multi-dimensional fixed arrays
jmh530 via Digitalmars-d-learn
digitalmars-d-learn at puremagic.com
Tue Jun 30 13:33:30 PDT 2015
On Tuesday, 30 June 2015 at 20:17:12 UTC, Justin Whear wrote:
> No. The order of braces when indexing is the opposite of the
> order when
> declaring.
> The declaration
>> int [1][2] foo;
> reads innermost to outermost, "((int [1] ) [2])"
>
> When indexing foo, you index from outermost to innermost, so
>> foo[1]
> means the second one-element array and
>> foo[1][0]
> means the first element of the second one-element array.
I think this is a good explanation.
Looking through
http://dlang.org/arrays.html
I see that the multidimensional array indexing is not
particularly focused on (could be improved?). I tend to prefer
reasoning things through than relying on a rule (more likely to
forget the rule). Thus, I would recommend the OP looks at the way
they describe the prefix array declarations for multidimensional
arrays. They have the example
int[4][3] b; // array of 3 arrays of 4 ints each
So you can think of b as an array containing 3 arrays with 4 ints
each. For the OP's foo, he should think of foo as an array
containing 2 arrays with 1 int each. Moreover, it's more likely
that you want to index the arrays and then what's in the arrays,
i.e. it's more likely that you would want to do something with
the first array of foo and then the second array of foo. This
notation makes it a little bit easier to do that.
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