Explain each of the following loops. Correct any problems you detect

(a)

    //do  // Need a block here.
    do {
      int v1, v2;
      cout << "Please enter two numbers to sum:" ;
      if (cin >> v1 >> v2)
      cout << "Sum is: " << v1 + v2 << endl;
    //while (cin);
    } while (cin);

(b)

    int ival;
    do {
      // ...
    //} while (int ival = get_response());  // Error: declaration in a do condition
    } while (ival = get_response());

(c)

    int ival;
    do {
      //int ival = get_response();  // Loop will define a new condition variable everytime
      ival = get_response();
    } while (ival);