I saw this question been asked at SO few hours ago.
My question is related to it but just a bit different and is a result of Johannes Schaub-litb's comment to Oli Charlesworth's answer.
Is i = (0, ++i, 0) undefined behavior?
P.S: This is just for educational purpose and has no relation with real life code or examples. Please ignore this question if you just want to add comments like "Why do you care? Nobody uses it in real world applications." etc
TIA
If i = (++i, 0) is defined, then so is this. Perhaps you should simplify the question!
No, it is not undefined behavior.
The only potential for undefined behavior here is the multiple modifications of i, but the one inside the () is isolated from the other by sequence points inherent in , operator. So, no undefined behavior.
I think that in i = (0, ++i, 0), i is modified at different sequence points, because of the comma operator, so therefore the behavior is defined.