Hacker News new | ask | show | jobs
by p0w3n3d 42 days ago
On my CS lectures algorithms professor used this pseudo language when writing an algorithm on a whiteboard :

  I <- I++
On the next hour another professor was giving lecture on C++ programming. I asked him the question: what would happen if we compiled

  i = i++
He went into some deep elaboration on it, but reassumed that only idiot would write like this...
1 comments
mywittyname 42 days ago
Out of curiosity, I checked if gcc would optimize i = i++ out, and it does!
link
_kst_ 41 days ago
What can be optimized out depends on the context.

If you write:

    int i = 0;
    i = i++;
and never use the value of i, the declaration and assignment are likely to be optimized out. (The behavior of the assignment is undefined, so this is a valid choice).

If you print the value of i, the compiler can still optimize away the computation, but is perhaps less likely to do so.

The solution, of course, is not to write code like that. Decide what you want to do, and write code that does that. "i = i++" will never be the answer to "how do I do this?", and wouldn't be even if the behavior were well defined. If you want i to be 1, write "int i = 1;".

link