Review of Class on Nov 23 : - PowerPoint PPT Presentation

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  1. Review of Class on Nov 23:

  2. Chapter 12: Structures and ADTs • Outline • Declaring Structures • Accessing a Member in a structure variable • Initialization of Structures • The use of typedef • Self-Referential Structures • Linear Linked Lists

  3. members of the structure Declaring Structures • How to declare a structure data type? • Example: a structure type to represent a date: Components: day, month, year struct date_str{ int day; int month; int year; }; • This declaration creates the derived date type struct date_str. structure tag name

  4. Declaring Structures • How to declare variables of a structure type? • Declare variables in declaration of a structure type • struct date_str{ int day; int month; int year; } date1, date2; • Declare variables “struct str_name variable_list;” • struct date_str{ int day; int month; int year; }; struct date_str date3, date4;

  5. Chapter 12: Structures and ADTs • Outline • Declaring Structures • Accessing a Member in a structure variable • Initialization of Structures • The use of typedef • Self-Referential Structures • Linear Linked Lists

  6. Access a member • How to access a member? • member operator “.” • structure_variable.member_name • Example: struct date_str{ int day; int month; int year; } date1, date2; date1.year = 2000; data2.year= 2005; date1.day = date2.day = 10; date1.month = date2.month = 11;

  7. Accessing a Member • How to access a member? • structure pointer operator -> access the members of a structure via a pointer. pointer_to_structure -> member_name  (*pointer_to_structure).member_name • Example: struct date_str *pDate = &date1; (*pDate).day  pDate->day

  8. Chapter 12: Structures and ADTs • Outline • Declaring Structures • Accessing a Member in a structure variable • Initialization of Structures • The use of typedef • Self-Referential Structures • Linear Linked Lists

  9. Initialization of Structures • Initialization • A structure variable can be followed by • an equal sign = and • a list of constants contained within braces • Example: struct date_str{ int day; int month; int year; }; struct date_str date={12, 12, 2000};

  10. Initialization of Structures • Initialization • If there are not enough values, the remaining members are assigned the value zero. • Example: struct student_str{ char last_name[15]; char first_name[15]; int UIN; int assign[6]; int midterm[3]; int final; } strcut student_str s1={“Bush”, “Jenny”, 80002211};

  11. Chapter 12: Structures and ADTs • Summary • Declaring Structures • Accessing a Member in a structure variable • member operator “.”: • structure_variable.member_name • structure pointer operator “ -> ” : • pointer_to_structure -> member_name • Initialization of Structures • A structure variable can be followed by • an equal sign = and • a list of constants contained within braces • If there are not enough values, the remaining members are assigned the value zero. Read Chapter 12.1 – 12. 6

  12. Class on Nov. 30

  13. Chapter 12: Structures and ADTs • Outline • Declaring Structures • Accessing a Member in a structure variable • Initialization of Structures • Self-Referential Structures • Linear Linked Lists • The use of typedef

  14. include <stdio.h> int main(void){ struct list{ int data; struct list *pNext; } a, b, c; struct list* p=&a; a.data=1; b.data=2; c.data=3; a.pNext = &b; b.pNext = &c; c.pNext = NULL; while (p!=NULL){ printf("%2d ", p->data); p = p->pNext; } }

  15. Self-Referential Structures • self-referential structures • structures with pointer members that pointto the structure type containing them. • Example: struct list{ int data; struct list *pNext; } a, b, c; member pNext points to the structure type struct list, which contains pNext as a member  struct list is a self-referential structure.

  16. Self-Referential Structures • Using self-referential structures to implement linear linked lists • struct list{ • int data; • struct list *pNext; • } a, b, c; • a.data=1; • b.data=2; • c.data=3; • a.pNext = &b; • b.pNext = &c; • c.pNext = NULL; 3 2 1 data pNext &c &b NULL c a b

  17. Chapter 12: Structures and ADTs • Outline • Declaring Structures • Accessing a Member in a structure variable • Initialization of Structures • Self-Referential Structures • Linear Linked Lists • The use of typedef

  18. Linear Linked Lists • What is linear Linked List? • How to implement linear linked lists • create a list • counting and lookup • insertion • deletion

  19. Linear Linked Lists • What is Linear Linked List? • data structure hang sequentially. • a head pointer that points to the first element of the list, • each element points at a successor element, • the last element having a link value NULL. • struct list{ • int data; • struct list *pNext; • } a, b, c; 2 1 3 data pNext &c &b NULL pHead

  20. Linear Linked Lists • Linear Linked Lists • A linked list is a very common data structure. • It can be used to implement efficient algorithms, such as sorting, searching.

  21. Linear Linked Lists • What is linear Linked List? • How to implement linear linked lists • create a list • counting and lookup • insertion • deletion

  22. data data data data data data Linear Linked Lists • How to implement linear linked lists • Consider the following list: ………… NULL pHead struct linked_list{ char data; struct linked_list *pNext; };

  23. Linear Linked Lists • Operations on a linked list Define functions such that • create a linked list • from a value of type char • from an array of type char • counting: the number of elements • looking up an element • inserting an element • deleting an element

  24. ‘A’ NULL pHead struct linked_list{ char data; struct linked_list *pNext; }; Linear Linked Lists • Operations on a linked list • create a linked list from a value: struct linked_list *create_value(char data); • return the head pointer of a link which contains a single item; the data field of this item is data. struct linked_list *pHead; pHead = create_value(‘A’);

  25. ‘A’ NULL pHead list.h #include <stdio.h> struct linked_list{ char data; struct linked_list *pNext; }; struct linked_list *create_value(char data); main.c #include "list.h" int main(){ struct linked_list *pHead; pHead = (struct linked_list *) create_value('A'); ……. } #include "list.h" struct linked_list *create_value(char data){ struct linked_list *pHead = NULL; pHead = (struct linked_list *) malloc(sizeof(struct linked_list)); pHead->data = data; pHead->pNext = NULL; return pHead; } list.c

  26. ‘a’ ‘b’ ‘c’ ‘d’ ‘e’ NULL pHead struct linked_list{ char data; struct linked_list *pNext; }; Linear Linked Lists • Operations on a linked list • create a linked list from an array: struct linked_list *create_array(char data_array[], int n); • return the head pointer of a link which contains n items; the data fields of the items are decided by data_array. char data_array[]={'a', 'b', 'c', 'd', 'e'}; struct linked_list * pHead; pHead = create_array(data_array, 5);

  27. ‘a’ ‘b’ ‘c’ ‘d’ ‘e’ NULL pHead #include <stdio.h> struct linked_list{ char data; struct linked_list *pNext; }; struct linked_list *create_array(char data_array[], int n); #include "list.h" int main(){ struct linked_list *pHead; char data_array[]={'a', 'b', 'c', 'd', 'e'}; pHead = create_array(data_array, 5); …… } main.c list.h struct linked_list *create_array(char data_array[], int n){ struct linked_list *p=NULL, *pHead = NULL; int i; if(n==0) return NULL; else{ pHead = (struct linked_list *) malloc(sizeof(struct linked_list)); pHead->data = data_array[0]; pHead->pNext = NULL; p = pHead; for (i=1; i<n;i++){ p->pNext = (struct linked_list *) malloc(sizeof(struct linked_list)); p->pNext->data = data_array[i]; p->pNext->pNext = NULL; p = p->pNext; } } return pHead; } list.c