Pointers and Array-Based Lists in C++

1. Chapter 3 Pointers and Array-Based Lists Data Structures Using C++

2. 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 Data Structures Using C++

3. 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 Data Structures Using C++

4. 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, * Data Structures Using C++

5. Pointers • Statements: int *p; int num; Data Structures Using C++

6. Pointers Data Structures Using C++

7. Pointers Data Structures Using C++

8. Pointers Data Structures Using C++

9. 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 Data Structures Using C++

10. Pointers Data Structures Using C++

11. Pointers x = 50; p = &x; Data Structures Using C++

12. Pointers *p = 38; Data Structures Using C++

13. Classes, structs, and Pointer Variables The syntax for accessing a class (struct) member using the operator -> is pointerVariableName->classMemberName Therefore, the statement (*studentPtr).gpa = 3.9; is equivalent to the statement studentPtr->gpa = 3.9; Data Structures Using C++

14. Classes, structs, and Pointer Variables Data Structures Using C++

15. Classes, structs, and Pointer Variables Data Structures Using C++

16. Syntax to use operator new new dataType; //to allocate a single variable new dataType[intExp]; //to allocate an array of variables Data Structures Using C++

17. Syntax to use operator delete delete pointer; //to destroy a single dynamic variable delete [] pointer; //to destroy a dynamically created array Data Structures Using C++

18. Operations on pointer variables • Assignment operations • Relational operations • Limited arithmetic operations Data Structures Using C++

19. Functions and Pointers void example(int* &p, double *q) { . . . } Data Structures Using C++

20. Pointers and Function Return Pointers int* testExp(...) { . . . } is a pointer of the type int. Data Structures Using C++

21. Shallow Versus Deep Copy and Pointers Data Structures Using C++

22. Shallow Versus Deep Copy and Pointers Data Structures Using C++

23. Shallow Versus Deep Copy and Pointers second = new int[10]; for(int j = 0; j < 10; j++) second[j] = first[j]; Data Structures Using C++

24. Classes and Pointers: Some Peculiarities class pointerDataClass { public: ... private: int x; int lenP; int *p; }; pointerDataClass objectOne; pointerDataClass objectTwo; Data Structures Using C++

25. Classes and Pointers: Some Peculiarities Data Structures Using C++

26. Destructor Data Structures Using C++

27. Destructor pointerDataClass::~pointerDataClass() { delete [ ] p; } class pointerDataClass { public: ~pointerDataClass(); ... private: int x; int lenP; int *p; }; Data Structures Using C++

28. Assignment Operator Data Structures Using C++

29. Assignment Operator Data Structures Using C++

30. Assignment Operator Data Structures Using C++

31. Overloading the Assignment Operator Function Prototype (to be included in the definition of the class): const className& operator=(const className&); Function Definition: const className& className::operator=(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; } Data Structures Using C++

32. 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 Data Structures Using C++

33. Copy Constructor Data Structures Using C++

34. Copy Constructor Data Structures Using C++

35. Copy Constructor Data Structures Using C++

36. 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 Data Structures Using C++

37. 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 Data Structures Using C++

38. Copy Constructor Data Structures Using C++

39. Copy Constructor General syntax to include the copy constructor in the definition of a class: className(const className& otherObject); Data Structures Using C++

40. Classes with Pointer Data Members • Include destructor in the class • Overload assignment operator for class • Include copy constructor Data Structures Using C++

41. 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; Data Structures Using C++

42. Array-Based Lists • List: A collection of elements of the same type • Length of list is number of elements in list Data Structures Using C++

43. 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 Data Structures Using C++

44. 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 Data Structures Using C++

45. UML Diagram of the class arrayListType Data Structures Using C++

46. Time Complexity of List Operations Data Structures Using C++

47. 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 Data Structures Using C++