Infinite Loop : Determining and breaking out of Infinite loop

Question

How would you determine a loop is a infinite loop and will break out of it.

Does anyone has the algorithm or can assist me on this one.

Thanks

Answer 1

There is no general case algorithm that can determine if a program is in an infinite loop or not for every turing complete language, this is basically the Halting Problem.

The idea of proving it is simple:

1. Assume you had such an algorithm A.
2. Build a program B that invokes A on itself [on B].
3. if A answers "the program will halt" - do an infinite loop
4. else [A answers B doesn't halt] - halt immidiately

Now, assume you invoke A on B - the answer will be definetly wrong, thus A doesn't exist.

Note: the above is NOT a formal proof, just a sketch of it.