Negative index for array in cpp

Question

while browsing through a queue examples, I came across

Its a queue example in which the indexes start from -1, but the program seems to be working fine

Is this valid, shouldn't this be a undefined behavior in some cases?

Which one of the 3 examples did you use? Arrays, linked list or stl? — Vlad
– Vlad, Commented Aug 2, 2012 at 13:57
Another line is rear = ++rear % MAX_SIZE; which is also UB. Please don't use that code at all! — Bo Persson
– Bo Persson, Commented Aug 2, 2012 at 14:01
I'd advise finding a different tutorial. You apparently already know more than the author... — Jerry Coffin
– Jerry Coffin, Commented Aug 2, 2012 at 14:21

Bill Lynch · Accepted Answer · 2012-08-02 13:59:20Z

2

You're correct. This code is invalid because it is dereferencing memory outside of that array.

answered Aug 2, 2012 at 13:59

Bill Lynch

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