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From: Sebastian Huber <sebastian-huber@web.de>
To: gcc-help@gcc.gnu.org
Subject: Re: Array Initialization warnings
Date: Wed, 24 Apr 2002 11:09:00 -0000
References: <3CC17386.5040608@keyed-upsoftware.com> <20020420155818.3c8ca837.liptak@isdd.sk> <3CC17545.E3E68FDE@tdcadsl.dk>
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Hello,
I think this identity between the dereference operator (is this the English 
translation?) and access via pointers is helpful:

T a [S_1][S_2]...[S_N];

a [i_1][i_2]...[i_n] <=> a
	+ i_1 * S_2 * ... * S_N_MINUS_1
	+ i_2 * S_3 * ... * S_N_MINUS_1
	+ ... +
	+ i_n

For example:

#include <iostream>

int main()
{
	int a [2][2][2][2] = {
		{ { { 0, 1 }, { 2, 3} }, { { 4, 5 }, { 6, 7 } } },
		{ { { 8, 9 }, { 10, 11} }, { { 12, 13 }, { 14, 15 } } }
	};
	for (int i = 0; i < 16; ++i) {
		cout << *(reinterpret_cast<int*>( a) + i) << endl;
	}
	std::cout << a [1][0][1][0]
		<< " == "
		<< *(reinterpret_cast<int*>( a) + 1 * 2 * 2 * 2 + 0 * 2 * 2 + 1 * 2 + 0)
		<< endl;
	return 0;
}

Ciao Sebastian

On Saturday 20 April 2002 16:03, you wrote:
> Hi guys,
>
> Michal Liptak wrote:
> > I think the internal representation of int[4][4] is the same as int[16]
> > m.
>
>  That is usually the case, i would think, but i am not sure, it
> is required by the standard, so i would not rely on that.
>
> bjorn