Exceptions, Pointers, and Reference

As my weeks seem to grow increasingly short I find myself this week between interviews and assignments brushing up on some of the old lecture notes from the classes previous two weeks in the hopes that I will be ready for the test. I felt in terms of value the last week has been one of the more enlightening in terms of long term impact. The focus had been on Exceptions and C++: pointers, and references.

Exceptions had been mostly a review but I found several fine points which I had yet to encounter. One of the first points was that in Java you can catch the exception if the heap/stack overflows where as C++ there is no nice way to do this. Another point that I hadn’t considered was in the case that you caught an exception but found you couldn’t handle the exception, in this case you can re-throw the exception caught and it will propagate up the call stack until the same exception is caught in the callers.

On the pointer/reference side of things I had always found that these constructs had been the source of many a bug in my code so it was nice to go through them again. The highlights were:

  • pointers can have the address they point to changed references can not(although both can have the value they point to changed if it is mutable)
  • pointers must be dereferenced(use * to access the value they point to rather than the address) to have there value manipulated where references do not need to be dereferenced
  • references are useful as aliases in the same function scope this does not serve much purpose but this proves useful to abstract out the complexity from the programmer in function argument passing(as compared to pass by pointer)
  • non-dynamic arrays are much like pointers, in fact you can dereference the pointer and select its zero-th value to prove this, however the sizeof function will return the total size of a non-dynamic array where as it will only return the size of the pointer argument on a dynamic array/pointer. In addition the allocations of the stack(non-dynamic arrays) must only have one name for the reference.
  • dereferencing the array + n is the same as a[n] if a is the array(aka: *(a+n) == a[n] for all integer values of n in which n is less than  the array length)

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