Pointers and Array-Based Lists

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Chapter 3

• Pointers and Array-Based Lists

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Chapter Objectives

• Learn about the pointer data type and pointer
  variables
• Explore how to declare and manipulate the pointer
  variables
• Learn about the address of operator and
  dereferencing operator
• Discover dynamic variables
• Examine how to use the new and delete operators
  to manipulate dynamic variables

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Chapter Objectives

• Learn about pointer arithmetic
• Discover dynamic arrays
• Become aware of the shallow and deep copies of
  data
• Discover the peculiarities of classes with
  pointer data members
• Explore how dynamic arrays are used to process
  lists

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Pointer Data Types and Pointer Variables

• Pointer variable variable whose content is a
  memory address
• Syntax to declare pointer variable
• dataType identifier
• Address of operator Ampersand,
• Dereferencing operator Asterisk,

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Pointers

• Statements
• int p
• int num

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Pointers
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Pointers
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Pointers
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Pointers

• Summary of preceding diagrams
• p, p, and p all have different meanings
• p means the address of p
• p means the content of p
• p means the content pointed to by p, that is
  pointed to by the content of memory location

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Pointers
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Pointers
x 50
p x
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Pointers
p 38
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Classes, structs, and Pointer Variables

• The syntax for accessing a class (struct) member
  using the operator -gt is
• pointerVariableName-gtclassMemberName
• Therefore, the statement
• (studentPtr).gpa 3.9
• is equivalent to the statement
• studentPtr-gtgpa 3.9

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Classes, structs, and Pointer Variables
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Classes, structs, and Pointer Variables
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Syntax to use operator new

• new dataType //to allocate a single
  variable
• new dataTypeintExp //to allocate an array of
  variables

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Syntax to use operator delete

• delete pointer //to destroy a single
  dynamic variable
• delete pointer //to destroy a
  dynamically created array

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Operations on pointer variables

• Assignment operations
• Relational operations
• Limited arithmetic operations

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Functions and Pointers

• void example(int p, double q)
• .
• .
• .

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Pointers and Function Return Pointers

• int testExp(...)
• .
• .
• .
• is a pointer of the type int.

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Shallow Versus Deep Copy and Pointers
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Shallow Versus Deep Copy and Pointers
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Shallow Versus Deep Copy and Pointers

• second new int10
• for(int j 0 j lt 10 j)
• secondj firstj

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Classes and Pointers Some Peculiarities

• class pointerDataClass
• public
• ...
• private
• int x
• int lenP
• int p
• pointerDataClass objectOne
• pointerDataClass objectTwo

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Classes and Pointers Some Peculiarities
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Destructor
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Destructor

• pointerDataClasspointerDataClass()
• delete p

• class pointerDataClass
• public
• pointerDataClass()
• ...
• private
• int x
• int lenP
• int p

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Assignment Operator
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Assignment Operator
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Assignment Operator
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Overloading the Assignment Operator

• Function Prototype (to be included in the
  definition of the class)
• const className operator(const className)
• Function Definition
• const className classNameoperator(const
  className rightObject)
• //local declaration, if any
• if(this ! rightObject) //avoid
  self-assignment
• //algorithm to copy rightObject into
  this object
• //return the object assigned
• return this

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Overloading the Assignment Operator

• Definition of function operator
• Only one formal parameter
• Formal parameter generally const reference to
  particular class
• Return type of function is reference to
  particular class

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Copy Constructor
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Copy Constructor
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Copy Constructor
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Copy Constructor

• If a class has pointer data members
• During object declaration, the initialization of
  one object using the value of another object
  would lead to a shallow copying of the data if
  the default memberwise copying of data is allowed
• If, as a parameter, an object is passed by value
  and the default member-wise copying of data is
  allowed, it would lead to a shallow copying of
  the data

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Copy Constructor

• The copy constructor automatically executes in
  the following situations
• When an object is declared and initialized by
  using the value of another object
• When, as a parameter, an object is passed by
  value
• When the return value of a function is an object

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Copy Constructor
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Copy Constructor

• General syntax to include the copy constructor in
  the definition of a class
• className(const className otherObject)

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Classes with Pointer Data Members

• Include destructor in the class
• Overload assignment operator for class
• Include copy constructor

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Overloading Array Index (Subscript) Operator ( )

• Syntax to declare the operator function operator
  as a member of a class for nonconstant
  arrays
• Type operator(int index)

• Syntax to declare the operator function operator
  as a member of a class for constant arrays
• const Type operator(int index) const

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Array-Based Lists

• List A collection of elements of the same type
• Length of list is number of elements in list

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Operations performed on a list

• Create the list initialized to an empty state
• Determine whether the list is empty
• Determine whether the list is full
• Find the size of the list
• Destroy, or clear, the list
• Determine whether an item is the same as a given
  list element

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Operations performed on a list

• Insert an item in the list at the specified
  location
• Remove an item from the list at the specified
  location
• Replace an item at the specified location with
  another item
• Retrieve an item from the list at the specified
  location
• Search the list for a given item

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UML Diagram of the class arrayListType
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Time Complexity of List Operations
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Chapter Summary

• Pointer data types and variables
• Dynamic variables
• Pointer arithmetic
• Dynamic arrays
• Shallow and deep copying
• Peculiarities of classes with pointer data
  members
• Processing lists