When accessing an element outside a dynamic array I get an exception.

I thought in D arrays will automatically expand themselves?

If not, how do I add an element to an array?

int[] arr = new int[1];
arr[1] = 34; // exception

If I change this to

int[] arr = new int[2];
arr[1] = 34;

Then it works. (similar to C/C++)

But my arrays will be growing and I do not know the final size ahead of time.

arr.add(34) does not work.

Try

arr ~= 33;

the ~= operator means append to. You can also do

auto a = [1,2] ~ [3,4];

which would give [1,2,3,4]

js.mdnq:

> When accessing an element outside a dynamic array I get an exception.
>
> I thought in D arrays will automatically expand themselves?

D dynamic arrays don't expand themselves "on demand" on array access, it's not efficient (and I think it's not a very clean operation, despite some languages do it). On the other hand D associative arrays grow if you add them key-values.


> arr.add(34) does not work.

To append to a dynamic array use:

arr ~= 34;

Bye,
bearophile

On 12/03/2012 04:43 PM, js.mdnq wrote:
> When accessing an element outside a dynamic array I get an exception.
>
> I thought in D arrays will automatically expand themselves?
>
> If not, how do I add an element to an array?
>
> int[] arr = new int[1];
> arr[1] = 34; // exception

Another option is to modify the length of the "slice" (yes, "slice", not "array"):

    arr.length = 100;

The following is almost mandatory reading: :)

  http://dlang.org/d-array-article.html

Ali