Adjust to the moving target called the C++ standard. Apparently nowadays it's not allowed to define an explicit copy constructor but not an assignment operator. Consequently, defining the explicit copy constructor in terms of the implicit/automatic assignment operator for general convenience no longer works. Add assignment operators. Caution: not tested with the IBM compiler, but there's no particular reason it shouldn't work.

/* Test file for Fahrenheit-Celsius conversion program FC4. */

  - 273.16 C         // Absolute zero
    0k
   +300k
    212f             // Boiling point of water
   -38.87C           // Melting point of mercury
   212 g             // Deliberate error
   +98.6 F           // Body temperature