4. Recovering from fail( ) State

• After

  
      cin.clear();
  
  

  the stream goes back to

  
      cin.good()
  
  

  state. Now what?

• Great news: the data in the input stream buffer hasn't been lost!
  For example,

  
  #include <iostream>
  using std::cin;
  using std::cout;
  int main()
  {
      int value = 0;
      cin >> value;
      if ( !cin ) {
          // cin is not good, more checks required:
          if ( cin.bad() ) {
              // cin is corrupted
              return 1; // signal error back to the operating system
          }
          if ( cin.eof() ) {
              // nothing to do: we want all inputs to end like this!
              return 0; // signal success to the operating system
          }
          if ( cin.fail() ) {
              cin.clear(); // go back to good state...
              // do something to recover...
              char ch = 0;
              while ( cin >> ch ) {
                  cout << "Recovered char(" << int( ch ) << ")\n";
              }
          }
      }
      // use value, everything is ok
      return 0;
  }