Isn''t it supposed to be the same as passing in the array buffer itself? What did I do wrong?? ..

    
void Test(float *f)	// temp function that prints the value

{
	int index;

	cout << "From H" << endl;
	for (index = 0; index < 10; index++)
		cout << f[index] << " ";
	cout << endl;
}

void main()
{

	int		index;		// looping var


	float	*array;
	array	= new float[10];		// a temp buf


	float **ref = NULL;				// the reference


	for (index = 0; index < 10; index++)	// initialize the buffer

		array[index] = (float)10 + index;

	ref = new float*[10];			// intitialize the references


	for (index = 0; index < 10; index++)	// set the reference in rev order

		ref[index] = &array[9 - index];

//	Test(array);		// this is ok

	Test(*ref);		// but this fails


	cout << "From main" << endl;
	for (index = 0; index < 10; index++)
		cout << *ref[index] << " ";
	cout << endl;

	delete	[]ref;
	delete	[]array;
}
    

Ok time to put the "head-wrecking pointer" thinking-cap on.
First off , your topic is wrong.
What your function is expecting is not an array of references, but a reference to an array (which is of course a pointer anyway, but I digress).

The first one array, is a reference to an array. SO your function accepts this fine.

What happens with the second is that you pass a reference to an array of references. The function prints out the first number because it is at the base address of *ref. but *ref isn''t equal to array so when it increments the pointer using the index it points to a completely different area of memory.

I''ll email you a diagram of what''s happening in memory if you like....

Woo.. That is head wrecking indeed. Thanks for the explanation there.

So is there anyway to keep the Func() unchanged but passing a ref to an array of references?..

I need to build a smaller array from the float array buffer which to pass to Func() fbut without the copying of the array elements. (eg. say I want to pass like say elements from 0 - 5 of the original array only but without allocating another float block)

Is that possible?

quote: I need to build a smaller array from the float array buffer which to pass to Func() fbut without the copying of the array elements. (eg. say I want to pass like say elements from 0 - 5 of the original array only but without allocating another float block)

Just pass a pointer to the beginning of the array, and the number of elements if that''s necessary. Only the pointer is copied, ie. 4 bytes, not the whole array.

-Jussi

quote: Original post by Selkrank
Just pass a pointer to the beginning of the array, and the number of elements if that''s necessary. Only the pointer is copied, ie. 4 bytes, not the whole array.
-Jussi

That would only work if the smaller array is sequential which will not be the case with mine.

Anyway I think I can avoid this ref to array of references. I''m thinking way too hard..