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  • I didn't even though that one could access an array with negative value ! Commented Sep 14, 2009 at 11:25
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    If it works, improve it. Commented Sep 14, 2009 at 11:37
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    @Clement: Remember, that in C and C++, array indexing obeys a[i] = *(a + i), it's just a simple address calculation, nothing fancy. If i is negative, you will access memory before the array starts. Of course this can change in C++ with an overloaded operator[](), but this is the base case. Commented Sep 14, 2009 at 12:10
  • You could also get a reference to the middle of an array, say b = a + 5. Then b[-5] would refer to a[0] and should be OK to access. Though it will confuse most programmers, so it is probably not a good idea. Commented Sep 14, 2009 at 12:21
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    @Clement: Negative indices are allowed, but going outside the bounds of the array is not. So if you use a negative index on the beginning of the array, it's bad, but if you have a pointer p to the third element, then p[-2] is perfectly legal. Commented Sep 14, 2009 at 13:04