Quick C question

[josh at offthehill.org (Josh ChaitinPollak)]

Don't use multidimensional arrays for image processing. You'll take  
huge speed hits and the compiler won't be able to optimize. Allocate  
a single dimensional N*M array and do the math to get to the pixels  
you need. You'll find it much easier to deal with in the long run.  
Not to mention for loops to deallocate the sub-arrays will get very  
old, very quickly.

Remember, C isn't Matlab.

-Josh

On Nov 16, 2005, at 10:54 AM, Anthony Gabrielson wrote:

> Thanks - That worked like a champ :).
>
> Anthony
>
> On Wed, 16 Nov 2005, Seth Gordon wrote:
>
>> Ooh!  Ooh!  Ooh!  Mr. Kotter!
>>
>>> #include <stdio.h>
>>>
>>> #define	D1	4
>>> #define	D2	2
>>>
>>> int main(){
>>>
>>> 	int *array;
>>
>> Here you're defining "array" as a pointer to an int.
>>
>>>
>>> 	array = malloc(sizeof(int) * (D1 * D2));
>>>
>>> 	array[1][1] = 32;
>>
>> Here you're using "array" as a pointer *to a pointer* to an int.
>>
>>>
>>> 	printf("Elem[1][1] = %d\n",array[1][1]);
>>> 	
>>> 	free(array);
>>>
>>> 	return 0;
>>> }
>>
>> Try changing "int *array" to "int **array".
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