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# Francesco Logozzo - Static Checking with Code Contracts for .NET

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• MP3 (Audio only)
• Low Quality MP4 (approx. 500-800kbps)
• Mid Quality WMV (Lo-band, Mobile)

Francesco Logozzo, a researcher at the Research in Software Engineering (RiSE) group at Microsoft Research, gives a demo of the Static Checker that comes with Code Contracts for .NET tools. The static checker allows you to verify that all the assertions in your code hold without actually running the code!

Francesco also goes to the whiteboard and gives us a short tutorial on Abstract Interpretation, the technique used by the static checker to prove the assertions.

The Research in Software Engineering team (RiSE) coordinates Microsoft's research in Software Engineering in Redmond, USA.

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• Abstract interpretation and static checking is a real cool thing. Thanks for sharing this and keep pushing in further developments on this!

Cheers, Matthias

• Great video and "promo" I've just started using CC.

Thank you very much.

• Some remark, or maybe qestion about simple example on whiteboard... since we always entering that loop with x increment we should get postcondition of x > 0 strictly... why do all reasoning with intervals leads to x in [0, +inf] interval?

• Hi Andrew,

that's a very good point.

(As far as x is concerned) the loop invariant is x >= 0, as before entering the loop  x == 0, and then it is always incremented by one.

At the loop exit, we know that x >=0, but also that x > N (by the negation of the loop guard) and N > 0 (by the method precondition).

As a consequence we can refine the interval for x to [2, +oo].

I haven't mentioned it in the video to keep it simple, but you are right that the tool can prove a stronger assertion after the loop. In fact, if you download the checker, you can see that it proves the assertions x > 0 and x > 1 (but not x > 2 .

Thanks!