What is the correct answer for cout << a++ << a;?

Question

Recently in an interview there was a following objective type question.

int a = 0;
cout << a++ << a;

Answers:

a. 10

Answer 1

The correct answer is to question the question. The statement is unacceptable because a reader cannot see a clear answer. Another way to look at it is that we have introduced side-effects (c++) that make the statement much harder to interpret. Concise code is great, providing it's meaning is clear.