Advanced Functions

1
Advanced Functions

• Day 10

2
Initializing Objects

• Member variables can be initialized in the body
  of the constructor
• or at initialization

CatCat() itsAge 5 itsWeight 8.3
CatCat() itsAge(5), itsWeight(8.3)
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Initializing Objects

• Member variables can be initialized in the body
  of the constructor
• or at initialization

CatCat(int age, float weight) itsAge
age itsWeight weight
CatCat(int age, float weight) itsAge(age), itsW
eight(weight)
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The Copy Constructorand Allocated Memory

• The copy constructor is called when a copy of an
  object is made
• When an object is passed by value into a function
• When an object is returned by value from a
  function
• The default copy constructor will copy pointers,
  but not allocated memory

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The Copy Constructorand Allocated Memory

• The pointers in the old and new object will both
  point to the same allocated memory.
• If the old object is destroyed, the allocated
  memory will be deleted, and the pointers in the
  new object will be invalid.

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Copying Objects With Allocated Memory
class Cat public Cat() Cat(const Cat
) Cat() int GetAge() const return
itsAge private int itsAge CatCat(
) itsAge new int itsAge
5 CatCat(const Cat rhs) itsAge new
int itsAge rhs.GetAge() CatCat()
delete itsAge itsAge NULL
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The Assignment Operator

• The compiler provides a default assignment
  operator operator ( )
• Cat Boots Frisky
• in addition to the constructor, copy
  constructor, and destructor
• Like the copy constructor, the assignment
  operator must be modified for objects which have
  allocated memory

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Operator Overloading

• Almost all C operators can be overloaded
• , --, , , /, ,
• This permits the operators to act on user defined
  types (classes)

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Overloading
class Cat public Cat operator () //
prefix Cat operator (int) // postfix
private int itsAge float
itsWeight Cat Catoperator ( ) //
prefix itsAge itsWeight .2 return
this
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Overloading
class Cat public Cat operator () //
prefix Cat operator (int) // postfix
private int itsAge float
itsWeight Cat Catoperator (int) //
postfix Cat temp this itsAge itsWeig
ht .2 return temp
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Overloading
class Cat public Cat operator (const Cat
) private int itsAge float
itsWeight Cat Catoperator (const Cat
rhs) Cat temp this temp.itsAge
rhs.GetAge() temp.itsWeight
rhs.GetWeight() return temp
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this

• Every class member function has a hidden
  parameter the this pointer
• this points to the individual object