std::cin infinite loop from invalid input [duplicate]

Answer 1

By default, std::basic_istream::ignore() ignores only 1 character:

basic_istream& ignore( std::streamsize count = 1, int_type delim = Traits::eof() );

(From http://en.cppreference.com/w/cpp/io/basic_istream/ignore)

More idiomatic use for your case seems to be the one from the example there:

cin.ignore(std::numeric_limits::max(), '\n');

Also, note that you want to call clear() before the ignore() call, so the input extraction of ignore() will succeed instead of returning immediately.