Simple array init question

[Daniel Keep]

Graham wrote:
> A bit of confusion here:-)  Yes, it's a simple, static fixed size,
> multi-dimensional array.  I could use a 1D array, but I wanted to try
> out the 2D approach and was puzzled why I couldn't use the initialiser
> for the entire array if I had more than one dimension.  There's nothing
> more to this!
> 
> Thanks.

You *don't* have more than one dimension; you're really nesting arrays.
 Strictly speaking, int[5][5] is an (albeit static) jagged array.

I realise that for your purposes, it's six of one, half a dozen of the
other -- I'm just being pedantic :)

	-- Daniel

> Daniel Keep wrote:
>>
>> Chris Nicholson-Sauls wrote:
>>> Daniel Keep wrote:
>>>> Graham wrote:
>>>>> A floating point texture buffer - 3 floats per pixel, and (say)
>>>>> 640x480
>>>>> pixels.
>>>>>
>>>>> Manfred Nowak wrote:
>>>>>> Graham wrote
>>>>>>
>>>>>>> several thousand elements large.
>>>>>> In what domains do one need to represent dense multidimensional
>>>>>> structures with O(1) time for accesses of elements?
>>>>>>
>>>>>> -manfred 
>>>> Perhaps you shouldn't be using jagged arrays, then.  int[][] is *NOT* a
>>>> multidimensional array.  It's basically equivalent to this:
>>>>
>>>> struct int_array
>>>> {
>>>>     int* ptr;
>>>>     size_t length;
>>>> }
>>>>
>>>> struct int_array_array
>>>> {
>>>>     int_array* ptr;
>>>>     size_t length;
>>>> }
>>>>
>>>> int_array_array buffer;
>>>>
>>>> Notice those nested pointers; that means that your texture is not
>>>> necessarily contiguous in memory, which would make, for example,
>>>> loading
>>>> the texture into GL a pain in the behind.  Not sure if the cache would
>>>> have problems...
>>>>
>>>> I think there's a few multidimensional array templates floating
>>>> around... or if not, you can always write your own :)
>>>>
>>>>     -- Daniel
>>>>
>>> Actually, /IF/ he's using static/fixed-length arrays, then as I
>>> understand it this ceases to be true.  That is, static arrays are solid
>>> blocks of memory -- and I assume this stays the same for
>>> multi-dimensional arrays.  Of course, /IF/ he's using dynamic-length
>>> arrays, then you're absolutely correct about it being likely opposite.
>>>
>>> -- Chris Nicholson-Sauls
>>
>> Ah yes, of course.  Sorry; bit dense today :P
>>
>>     -- Daniel
>>

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{
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              // guaranteed to be random.
}

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