未理解的程序（2014.5.17）

#include<iostream>


using std::cout;
using std::endl;
using std::cin;


int main()
{
int x;
cout << "Before a bad input operation:"
<< "\ncin.rdstate(): " << cin.rdstate()
<< "\n cin.eof(): " << cin.eof()
<< "\n cin.fail(): " << cin.fail()
<< "\n cin.bad(): " << cin.bad()
<< "\n cin.good(): " << cin.good()
<< "\n\nExpects an integer, but enter a character: ";
cin >> x;


cout << "\nAfter a bad input operation:"
<< "\ncin.rdstate(): " << cin.rdstate()
<< "\n cin.eof(): " << cin.eof()
<< "\n cin.fail(): " << cin.fail()
<< "\n cin.bad(): " << cin.bad()
<< "\n cin.good(): " << cin.good() << "\n\n";


cin.clear();


cout << "After cin.clear()"
<< "\ncin.fail(): " << cin.fail()
<< "\ncin.good(): " << cin.good() << endl;


return 0;

}