As an exercise in Barjne Strousups book he asks to make a list of five constructs which are undefined in C++ and five constructs which are implementation specific.
I couldn't come up with five of each, but thought it would be a good resource if you could list any examples you can think of.
Here is what I came up with from the text.
incrementing/decrementing past the max size of the argument type.
2. Division by Zero
3. subexpression evaluation
int i=f(1)+g(2);// cannot assume left to right evaluation.
The only one I could come up with that is implementation dependant is:
The definition of NULL;
Feel free to add your own