// Try it...

#include <iostream>
#include <string>
#include <limits>

using namespace std;

int main(){
  int i;
  while (true){
    cout << "Enter a number: ";
    cin >> i;                                             // cin is converted to 'a boolean value'
                                                          // via an implicit conversion operator - while cin is in a good state
    cout << "We got: " << i << " " << endl;
  
    if (cin.good())
      cout << "cin is good" << endl;
    else if (cin.eof())
      cout << "cin is at EOF" << endl;                    // when typing Cntrl D
    else if (cin.fail())                   
      cout << "cin has failed" << endl;                   // when typing a non-digit
    else if (cin.bad())
      cout << "cin is in really bad shape" << endl;

    cin.clear();
    cin.ignore(numeric_limits<streamsize>::max(), '\n');  // flush input
  }  
}