On 04/18/2013 07:20 AM, ixid wrote:
Jacob Carlborg said:
>> An array is represent using a struct with a pointer to the array data
>> and the length, like this:
>>
>> struct Array
>> {
>> void* ptr;
>> size_t length;
>> }
The terms "array" and "slice" are commonly interchanged but I think it
adds to the confusion. The above is the definition of a slice. An array
is simply a collection of objects placed next to each other.
>> The struct is passed by value, but since it contains a pointer to the
>> data it will be passed by reference. Note that if you do:
>>
>> void foo (int[] a)
>> {
>> a ~= 3;
>> }
>>
>> auto b = [3, 4];
>> foo(b);
>>
>> The caller will not see the change made by "foo".
>>
>> Don't know if this explanation helped you to understand.
>
> What does a fixed length array look like when passed, doesn't it have a
> similar payload of data and length?
No. It is all of the elements side by side. That is the definition of an
array.
int[3] a;
assert(a.sizeof == ((a[0]).sizeof * a.length));
assert(cast(void*)&a == cast(void*)&(a[0]));
A fixed-length array does not have a ptr or length member. The former is
simly the address of the fixed-length array itself and the latter is a
compile-time constant.
> I take it you mean the struct method
> is the variable length array.
Yes. The struct above is a slice. (Although, in reality length is
defined before ptr.)
Ali
