When using a 2 dimensional array (such as array[2][2]) is it any slower than using a 1 dimensional array and doing the indexing myself. Would one of these be faster than the other: int a = array[r][c]; or int a = array[r*2 + c];

If it''s a statically allocated array i.e.
int array[5][4];
then it''s the same speed. The compiler does the same computation for you.

if its not a static array, it takes two derefernces for a 2D array, instead of one deference for a 1d array.