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Calling the Base-Class Constructor

• The constructor of a derived class has two tasks:
  • Initialize the base object.
  • Initialize all data members.
• Frequently, a derived-class constructor must invoke the base-class constructor before initializing the derived-class data.
• Here, we call the Clock constructor with the parametermil before executing the code inside the {}.

  TravelClock::TravelClock(bool mil, string loc, int diff)
     : Clock(mil)
  {
     location = loc;
     time_difference = diff;
     while (time_difference < 0)
        time_difference = time_difference + 24;
  };
  

• If you omit the base-class constructor, then the base object is constructed with the default constructor of the base class.
• If the base class has no default constructor, then you have to explicitly call the base-class constructor in the derived-class constructor.

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