LINKED LIST IMPLEMENTATION OF STACK

LINKED LIST IMPLEMENTATION OF STACK

Aim

            To demonstrate linked list implementation of stack using a C program.

Algorithm

            Step 1: [Include all the necessary header files]

            Step 2: [Declare the Variables]

            Step 3: Read operator

            Step 4: IF opt <---THEN

                        Step 4.1: READ n

                        Step 4.2: WHILE (n        n-1)

                                    Step 4.2.1: READ d

                                    Step 4.2.2: CALL INSERT( start , d)

                        Step 4.3: [End of while Structure]

            Step 5: IF opt         2 THEN

                        Step 5.1: READ x

                        Step 5.2: CALL del(start,x)

            Step 6: IF opt            3 THEN

                        Step 6.1: READ x

                        Step 6.2: CALL FIND

            Step 7: IF opt         4 THEN

                        Step 7.1: READ x

                        Step 7.2: CALL FINDPREVIOUS

Step 8: IF opt         5 THEN

                        Step 8.1: READ x

                        Step 8.2: CALL FINDNEXT(start, x)

Step 9: IF opt         6 THEN

            CALL len(Start)

Step 10: IF opt         7 THEN

            CALL printlist(Start)

Step 10: IF opt         8 THEN

            CALL erase (Start)

Step 12: [End of Main]

Algorithm For Find(struct node*p, int x, int *pos)

            Step 1: temp          p

            Step 2 :*pos         1

            Step 3: IF ( TEMP        NULL) THEN

                        RETURN NULL

                        ELSE

                        WHILE ( TEMP!= NULL && TEMP          DATA!= X)

                        ASSIGN 1 TO *POS+1 AND TEMP’S LLINK FIELD TO TEMP

                        RETURN THE TEMP

Algorithm for Previous (struct node*p, int x)

            Step 1: temp          p

            Step2: IF ( TEMP        NULL) THEN

                        RETURN NULL

                        ELSE

                        WHILE (TEMP        LINK != NULL && TEMP       LINK      DATA!= X)

                       

ASSIGN TEMP’S LINK FIELD TO TEMP

                        RETURN THE TEMP

Algorithm For Find next(struct node*p, int x)

            Step 1: temp          p

            Step2: IF ( TEMP        NULL) THEN

                        RETURN NULL

                        ELSE

                        WHILE (TEMP        LINK != NULL && TEMP      DATA!= X)

                        ASSIGN TEMP’S LLINK FIELD TO TEMP

                        RETURN THE TEMP’S LINK FIELD

Coding:

                        #include<stdio.h>

#include<conio.h>

#include<stdlib.h>

push();

void pop();

void display();

struct node

{

            int data;

            struct node *next;

}*top=NULL;

void main()

{

            int ch;

            clrscr();

            printf("\n\n1.Push\n\n2.Pop\n\n3.Display");

            do

            {

                        printf("\n\nEnter your Choice :: ");

                        scanf("%d",&ch);

                        switch(ch)

                        {

                                    case 1:

                                                push();

                                                break;

                                    case 2:

                                                pop();

                                                break;

                                    case 3:

                                                printf("\n\nContents of stack :: \t");

                                                display();

                                                break;

                                    default:

                                    printf("\n\nInvalid Choice......");

                                    getch();

                                    exit(0);

                        }

            }while(ch<4);

            getch();

}

push()

{

            int x;

            struct node *newnode;

            newnode=malloc(sizeof(struct node));

            printf("\n\nEnter the number to be pushed into the stack :: ");

                        scanf("%d",&x);

            newnode->data=x;

            if(top==NULL)

            {

                        newnode->next=top;

                        top=newnode;

            }

            else

            {

                        newnode->next=top;

                        top=newnode;

            }

            printf("\n\nNumber pushed is %d",x);

            return(x);

            }

void pop()

{

            struct node *t;

            if(top==NULL)

                        printf("\n\nStack Underflow");

            else

            {

                        t=top;

                        top=top->next;

                        printf("\nDeleted element is %d",t->data);

                        free(t);

            }

            getch();

}

void display()

{

            struct node*i;

            for(i=top;i!=NULL;i=i->next)

                        printf("%d , ",i->data);

            if(top==NULL)

                        printf("Stack is empty");

            getch();

}

Output:

1.Push

2.Pop

3.Display

Enter your Choice :: 1

Enter the number to be pushed into the stack :: 5

Number pushed is 5

Enter your Choice :: 1

Enter the number to be pushed into the stack :: 10

Number pushed is 10

Enter your Choice :: 3

Contents of stack :: 10 , 5 ,

Enter your Choice :: 2

Deleted element is 10

Enter your Choice :: 3

Contents of stack ::  5 ,

Enter your Choice :: 5

Invalid Choice......