C++异常处理

while ( cin >> item1 >> item2 ）{try{if ( !item1.same_isbn(item2) )throw runtime_error("Data must refer to same ISBN");cout << item1 + item2 << endl;}catch (runtime_error err){cout << err.what() << "\nTry again: Entry Y or N" << endl;char c;cin >> c;if ( cin && c == 'N' )break;}}