cin.clear(ios_base::failbit) vs cin.setstate(ios_base::failbit)

Question

For one of my assignments, I was told to use cin.clear(ios_base::failbit) to set the failbit. I wonder, what is the difference between cin.clear(ios_base::failbit) and cin.setstate(ios_base::failbit)? Is the latter not clearer? I am a bit surprised to see how the failbit is set with clear(). Why such a counter-intuitive way for using clear()?

Answer 1

I am a bit surprised to see how the fail bit is set with clear(). Why such a counter-intuitive way for using clear()?

Well let's think about it.

 std::cin.setstate(ios_base::failbit);

This will set the fail bit if it isn't already set, but preserve any other stream error state for std::cin.

 std::cin.clear(ios_base::failbit);

This will clear all the stream error state from std::cin and then set only the fail bit.