const double PI = 3.14159;

1

• const double PI 3.14159
• class Sphere
• public
• Sphere()
• Sphere(double initialRadius)
• void SetRadius(double newRadius)
• double GetRadius() const
• double GetDiameter() const
• double GetCircumference()
• double GetArea() const
• double GetVolume() const
• void DisplayStatistics() const
• private
• double theRadius

2
Scope resolution operator

• Sphere
• Precede each member function name
• Distinguishes it from any other function

3
Default Constructor

• SphereSphere() theRadius (1.0)
• Sphere unitSphere //invokes the default
  constructor

4
Constructor

• SphereSphere() (double initialRadius)
  theRadius (initialRadius)
• Sphere mySphere(5.1)
• Invokes above constructor with the value 5.1

5
Initializer

• Data member name followed by its initial value
  enclosed in parentheses
• SphereSphere() theRadius(1.0)
• Multiple initializers separated by commas
• Initializer can only be used with constructors

6
Constructor defaults

• If you omit all constructors-
• Compiler-generated Default Constructor
• No arguments
• If you define a constructor with arguments, but
  no default
• No default constructor
• Cannot do
• Sphere defaultSphere

7
sphere.cpp

• SphereSphere() theRadius (1.0)
• SphereSphere(double initialRadius)
• if (initialRadius gt 0)
• theRadius initialRadius
• else
• theRadius 1.0
• void SphereSetRadius(double newRadius)
• if (newRadius gt 0)
• theRadius newRadius
• else
• theRadius 1.0

8

• double SphereGetRadius() const
• return theRadius
• double SphereGetDiameter() const
• return 2.0 theRadius
• double SphereGetCircumference() const
• return PI 2.0 theRadius
• double SphereGetArea() const
• return 4 PI theRadius theRadius
• double SphereGetVolume() const
• double radiusCubed theRadius theRadius
  theRadius

9

• bool SphereEqual(Sphere otherSphere)
• return (radius otherSphere.radius)
• void SphereDisplayStatistics() const
• cout ltlt "\nRadius " ltlt GetRadius()
• ltlt "\nDiameter " ltlt GetDiameter()
• ltlt "\nCircumference " ltlt
  GetCircumference()
• ltlt "\nArea " ltlt GetArea()
• ltlt "\nVolume " ltlt GetVolume()
• ltlt endl

10
client

• include ltiostream.hgt
• include "Sphere.h"
• int main()
• Sphere unitSphere
• Sphere mySphere(5.1)
• unitSphere.DisplayStatistics()
• mySphere.setRadius(4.2)
• cout ltlt mySphere.GetDiameter() ltlt endl
• if (unitSphere.Equal(mySphere))
• cout ltlt "Spheres are equal" ltlt endl
• return 0

11
Friend of a class

• class Sphere
• friend bool Equal(Sphere sphere1, Sphere
  sphere2)
• //
• bool Equal( / in / Sphere firstSphere,
• / in / Sphere secondSphere)
• return (firstSphere.radius
  secondSphere.radius)

12
Friend

• Defined outside the scope of a class
• Nonmember function
• Has access to the private data members
• Friend appears only in prototype
• Allows more traditional syntax
• Equal(sphere1,sphere2)
• must use dot notation within implementation of
  Equal

13
Operator Overloading

• Overloaded operator has multiple meanings
• Operator with more than one meaning
• integer addition, float addition
• 2 3 //integer addition
• 2.0 3.0 //float addition
• C class instance only allowed assignment() and
  member selection(.)
• operator function - allows built-in operators to
  apply to class instances
• operator ltsymbolgt

14
Guidelines for Overloading Operators

• You can overload any operator except
• . . ? sizeof
• You cannot define new operators by overloading
  symbols that are not already operators in C
• You cannot change the standard precedence of a
  C operator or the number of its operands
• At least one operand of an overloaded operator
  must be an instance of a class
• A typical class should overload at least the
  assignment operator(), the equality( and !)
  and the relationsl(lt,lt,gt,gt) operators.
• You cannot change the number of arguments for an
  overloaded method.
• Model conventional use of operator

15

• class Sphere
• public //can be accessed by client
• ...
• bool operator (Sphere otherSphere) const
• private //can be accessed by member functions
• double theRadius //member variables
• if (sphere1.Equal(sphere2))//using a member
  function
• if (Equal(sphere1,sphere2) //using a friend
  function
• if (sphere1sphere2) //using an operator
  function

16
I/O

• istream cin //instance of class
• ostream cout
• cin.get(someChar) //invoke function
• cin.ignore(200,'\n')
• ifstream dataFile
• dataFile.open("input.dat")
• ltlt and gtgt are overloaded