CSci 152: Programming II Fall 2004

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CSci 152 Programming IIFall 2004

• Composition

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• COMPOSITION
• In composition one (or more) member(s) of a class
  is an object of another class type.
• Composition is a has-a relation.

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• class dateType
• public
• void setDate(int month, int day, int year)
• void getDate(int month, int day, int
  year)
• void printDate() const
• dateType(int month, int day, int year)
• dateType()
• private
• int dMonth //variable to store the month
• int dDay //variable to store the day
• int dYear //variable to store the year

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• void dateTypesetDate(int month, int day, int
  year)
• dMonth month
• dDay day
• dYear year
• void dateTypegetDate(int month, int day,
• int year)
• month dMonth
• day dDay
• year dYear
• void dateTypeprintDate() const
• coutltltdMonthltlt"-"ltltdDayltlt"-"ltltdYear

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• //constructor with parameter
• dateType dateType(int month, int day, int year)
  
• dMonth month
• dDay day
• dYear year
• dateType dateType() //default parameter
• dMonth 1
• dDay 1
• dYear 1900

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• class personalInfo
• public
• void setpersonalInfo(string first, string
  last,
• int month, int day, int year, int
  ID)
• void printpersonalInfo () const
• personalInfo(string first, string last,
• int month, int day, int year, int ID)
• personalInfo()
• private
• personType name
• dateType bDay
• int personID

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• personalInfo student
• When the object student enters its scope, the
  objects bDay and name, which are members of
  student, also enter their scopes as a result,
  one of their constructors is executed.
• The arguments to the constructor of a
  member-object (such as bDay) are specified in the
  heading part of the definition of the constructor
  of the class.
• Member-objects of a class are constructed in the
  order they are declared (not in the order they
  are listed in the constructors member
  initialization list), and before the enclosing
  class objects are constructed.
• The object name is initialized first, then bDay,
  and finally student.

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• void personalInfosetpersonalInfo(string first,
• string last, int month, int day, int year,
  int ID)
• name.setName(first,last)
• bDay.setDate(month,day,year)
• personID ID
• void personalInfoprintpersonalInfo () const
• name.print()
• coutltlt"s date of birth is "
• bDay.printDate()
• coutltltendl
• coutltlt"and personal ID is "ltltpersonID

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• personalInfopersonalInfo(string first, string
  last,
• int month, int day, int year, int ID)
• name(first,last), bDay(month,day,year)
• personID ID
• personalInfopersonalInfo() //default
  constructor
• personID 0

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• In the case of inheritance we use the class name
  to invoke the base classs constructor while in
  the case of composition we use the member object
  name to invoke the constructor of the member
  object.