![Cont …
Here we have given the structure of a typical
node:
struct node {
char name[20]; // Name of up to 20 letters
int age;
float height; // In metres
node *nxt;// Pointer to next node
};struct node *start_ptr = NULL;](https://image.slidesharecdn.com/dsa-ch3-231216102705-7692f5f2/85/Data-structure-and-algorithms-chapter-three-LINKED-LIST-19-320.jpg)
Data structure and algorithms chapter three LINKED LIST
- 2. Review on pointer • Each variable is assigned a memory slot (the size depends on the data type) and the variable’s data is stored there • A pointer is a variable used to store the address of a memory cell.
- 3. Cont… • Declaration of Pointer variables type* pointer_name; //or type *pointer_name; where type is the type of data pointed to (e.g. int, char, double)
- 4. • The "address of " operator (&) gives the memory address of the variable – Usage: &variable_name #include <iostream> using namespace std; void main(){ int a, b; a = 88; b = 100; cout << "The address of a is: " << &a << endl; cout << "The address of b is: " << &b << endl; Result is: The address of a is: 1020 The address of b is: 1024
- 5. Cont.. We can access to the value stored in the variable pointed to by using the dereferencing operator (*), int a = 100; int *p = &a; cout << a << endl; cout << &a << endl; cout << p << " " << *p << endl; cout << &p << endl; Result is: 100 1024 1024 100 1032
- 6. Review on Structures Structures are aggregate data types built using elements of primitive data types. The struct keyword creates a new user defined data type that is used to declare variables of an aggregate data type. Structure variables are declared like variables of other types. • Syntax: struct <structure tag> <variable name>; E.g. struct Time timeObject, struct Time *timeptr;
- 7. Cont… Accessing Members of Structure Variables • The Dot operator (.): to access data members of structure variables. • The Arrow operator (->): to access data members of pointer variables pointing to the structure. • E.g. Print member hour of timeObject and timeptr. cout<< timeObject.hour; or cout<<timeptr->hour; TIP: timeptr->hour is the same as (*timeptr).hour.
- 8. What is linked list? Linked list is a data structure used for storing collections of data. linked list have the following properties: 1. successive elements are connected by pointers 2. Last elements points to Null 3. Can grow or shrink in size during program execution 4. Can be made just as long as required(until system memory exhausts)
- 9. Cont… A linked list is made up of a chain of nodes. Each node contains: • the data item- holds actual elements on the list • a pointer to the next node- address of the next/prev node in the list
- 10. Cont…
- 11. Array vs. linked list Arrays -simple and easy to use -faster access to the elements -fixed size -complex position based insertion Linked list - Dynamic memory allocation - Easy position based insertion
- 12. Dynamic memory allocation Dynamic memory allocation is when an executing program requests that the operating system give it a block of main memory. The program then uses this memory for some purpose. Usually the purpose is to add a node to a data structure. In object oriented languages, dynamic memory allocation is used to get the memory for a new object.
- 13. Types of linked lists 1.singly linked list 2. Doubly linked list
- 14. Singly linked list A singly linked list can be represented by a diagram like shown blow:
- 15. Cont… Start (Head): Special pointer that points to the first node of a linked list, so that we can keep track of the linked list. The last node should points to NULL to show that it is the last link in the chain (in the linked list).
- 16. Creating Linked Lists in C++ • A linked list is a data structure that is built from structures and pointers. • It forms a chain of "nodes" with pointers representing the links of the chain and holding the entire thing together. • A linked list can be represented by a diagram like this one:
- 17. Cont… According to the above example in the figure, it is the singly linked list which has four nodes in it, each with a link to the next node in the series (in the linked list).
- 18. Defining the data structure for a linked list The key part of a linked list is a structure, which holds the data for each node (the name, address, age or whatever for the items in the list), and, most importantly, a pointer to the next node.
- 19. Cont … Here we have given the structure of a typical node: struct node { char name[20]; // Name of up to 20 letters int age; float height; // In metres node *nxt;// Pointer to next node };struct node *start_ptr = NULL;
- 20. Adding a node to the list Steps 1. Allocate a new node 2. Set the node data values and make new node point to Null 3. Make old last node’s next pointer point to the new node 4. *make the new last node’s prev pointer point to the old last node.(this is only for DLL)
- 21. Cont… • Insert at the front Steps allocate a new node Insert new element values Make the next pointer of the new node point to old head(start) Update head to point to the new node
- 22. Example
- 23. cont… • Insert at the end Steps Allocate a new node Set the node data values and make the next pointer of the new node point to null Make old last node’s next pointer point to the new node Update end to point to the new node
- 24. Cont … • Insertion in the middle Steps Create a new node Set the node data values Break pointer connection Reconnect the pointers
- 25. Deleting the 1st node in SLL
- 27. Double linked list(DLL) • A doubly linked list is one where there are links from each node in both directions: • each node in the list has two pointers, one to the next node and one to the previous one - again, the ends of the list are defined by NULL pointers.
- 28. DLL…
- 29. Defining DLL