Holding a pointer to a multidimensional array without breaking it's structure.

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November 28th, 2004, 03:38 AM

BLiND_LiMiT

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pointer to a multidimensional array

Hi,

How can I declare a pointer to a multi-dimensional array without losing the benefits granted from using a multi-dimensional array?

EG.

Code:

const char c_cMap[4][4] = {
	{1, 0, 1, 0},
	{1, 0, 1, 0},
	{1, 0, 1, 0},
	{1, 0, 1, 0},
};

//char* pcPointerToMap[4][4]...?
// I want to use the pointer to access the array in the same way as I could the constant.

November 28th, 2004, 06:34 AM

grumpy

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To declare a pointer to a multi-dimensional array, the most practical way is to use a typedef.

PHP Code:


		
			
 typedef char MyMap[4][5];

typedef MyMap *PointerToMyMap;



int main()

{

     MyMap a_map;

     char another_map[4][5];

     MyMap *a_pointer;

     PointerToMyMap another_pointer;



     a_pointer = &a_map;

     a_pointer = &another_map;

     

     another_pointer = &a_map;

     another_pointer = &another_map;

     another_pointer = a_pointer;  

}

Keep in mind that typedef simply declares a new name for an existing type, which is why the above example will be valid on every line.

It is technically possible to do the same without typedefs, but the syntax is somewhat more cryptic, difficult to understand, and easy to get confused with. Hence the typedef type approach is usually recommended for this sort of problem.

The typedef approaches also works nicely with more challenging problems such as declaring a pointer to a multi-dimensional array of function pointers. The solution to that problemn without typedef's is far from being a thing of beauty.

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Last edited by grumpy : November 28th, 2004 at 06:47 AM.

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