Question: What is wrong with this piece of code?

1. The main function is supposed to have a void return type.
2. `std::cin` and `std::cout` are invalid. The correct names for the character input and output streams are `cin` and `cout`.
3. The address of `str` is supposed to be used. That is `&str` instead of `str`.
4. The input operator flow is inverted. it should start from `std::cin` and then flow (>>) into `str`.

Answer: The correct answer of the above question is Option D:The input operator flow is inverted. it should start from `std::cin` and then flow (>>) into `str`.