Classes Copy Constructors

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Classes Copy Constructors
Department of Computer and Information
Science,School of Science, IUPUI
CSCI 240
Dale Roberts, Lecturer Computer Science,
IUPUI E-mail droberts_at_cs.iupui.edu
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Copy Constructor

• Constructor with a Reference to THAT CLASS as an
  ARGUMENT
• X(X ) Format
• Initialization of a New Object by Another Object
  of that Class
• An Object is Passed by Value to a Function
• An Object is Returned from a Function
• Shallow and Deep Copying -- Involvement of
  Pointers
• Implicit Copy Constructor is Created by the
  Compiler to Perform Member-wise Initialization

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Copy Constructor Example 1

• // date.hdefine size 50 class date
  private int day, month, year char
  string_date public date(char ip_date)
  //Constructor date(const date ip_date) //
  Copy Constructor date() //Destructor void
  print_date() //Member Function

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Copy Constructor Example 1 .

• // date.cppinclude date.hDatedate() //defa
  ult constructor day 0 month 0 year 0
  string_date 0datedate(char ip_date)
  //Constructor day 0 month 0 year 0
  string_date new char size
  strcpy(string_date, ip_date) //Shallow Copy
  Constructor date(const date ip_date)
  string_date ip_date.string_date
  //Destructor datedate() delete
  (string_date)

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Copy Constructor Example 1 .

• // client.cppinclude date.hmain()
  date today("June 21, 1995") //Use of shallow
  copy constructor date extra_day today
• Shallow copy simply means that all the data
  member values are copied.

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Copy Constructor Example 2

• // date.hdefine size 50 class date
  private int day, month, year char
  string_date public date(char ip_date)
  //Constructor date(const date ip_date) //
  Copy Constructor date() //Destructor
  void print_date() //Member Function

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Copy Constructor Example 2 .

• // date.cppinclude date.hDatedate() //defa
  ult constructor day 0 month 0 year 0
  string_date 0datedate(char ip_date)
  //Constructor day 0 month 0 year 0
  string_date new char size
  strcpy(string_date, ip_date)//Deep Copy
  Constructor date(const date ip_date)
  string_date new charsize
  strcpy(string_date, ip_date.string_date)
  //Destructor datedate() delete
  (string_date)

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Copy Constructor Example 2 .

• // client.cppinclude date.hmain()
  date today("June 21, 1995") //Deep copy
  constructor date extra_day today
• Deep copy means that objects pointed to by data
  members are also copied. Deep copying may be
  required whenever you have data members that are
  pointers.

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Copy Constructor - Example 3

• // student.h/ A Simple Class to Represent a
  Student /define size 50class Student 
  private char name char id char email 
  public Student(char , char , char
  ) Student(Student ) //Copy
  constructor Student()

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Copy Constructor Example 3 .

• // student.cppinclude student.h/ Member
  functions of the Student" class /Student
  Student(char studentName, char studentId,
  char studentEmail) name new charsize
     strcpy(name, studentName) id new
  charsize    strcpy(id, studentId) email
  new charsize    strcpy(email,
  studentEmail)StudentStudent() delete
  name delete id delete
  email//Shallow copy constructorStudentStuden
  t (Student s) name s.name id
  s.id email s.email

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Copy Constructor Example 3 .

• // client.cppinclude student.h/ csStudent"
  is an instance of Student" /main()   
  Student csStudent1("Susie Creamchese,
  "123456789, "screamch_at_iupui.edu")   
  Student csStudent2 csStudent1

What happens when csStudent2 changes its name?
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Copy Constructor - Example 4

• // student.h/ A Simple Class to Represent a
  Student /define size 50class Student 
  private char name char id char email 
  public Student(char , char , char
  ) Student() Student(Student ) //Copy
  constructor

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Copy Constructor Example 4 .

• // student.cppinclude student.h/ Member
  functions of the Student" class
  /StudentStudent(char studentName, char
  studentId, char studentEmail) name new
  charsize    strcpy(name, studentName) id
  new charsize    strcpy(id, studentId)
  email new charsize    strcpy(email,
  studentEmail)StudentStudent() delete
  name delete id delete email//
  Deep copy constructorStudentStudent(Student
  s) name new charsize strcpy(name,
  s.name) id new charsize
  strcpy(id, s.id) email new charsize
  strcpy(email, s.email)  

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Copy Constructor Example 4 .

• // client.cppinclude student.hmain()   
  Student csStudent1 (Susie Creamchese,
  123456789, screamch_at_iupui.edu)   
  Student csStudent2 csStudent1

What happens when csStudent2 changes its name?
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Acknowledgements

• These slides were originally prepared by Rajeev
  Raje, modified by Dale Roberts.