The document discusses implementation of linked lists in C programming language. It includes functions to create, insert, delete and display nodes in a linked list. The functions demonstrated are to insert nodes at the beginning, end or after a particular node. It also includes functions to delete nodes from the beginning, end or anywhere in the list. The main function uses a switch case to call these functions and operate on a linked list based on user input.

1. /* IMPLEMENTATION OF THE STACK USING ARRAYS */
/* STACK_A.C */
# include<stdio.h>
# include<string.h>
# include<ctype.h>
#include<conio.h>
# define size 3
int top = -1;
int flag = 0;
int stack[size];
void push(int *, int);
int pop(int *);
void display(int *);
/* Definition of the push function */
void push(int s[], int d)
{
if(top ==(size-1))
flag = 0;
else
{ flag = 1;
++top;
s[top] = d;
}
}
/* Definition of the pop function */
int pop(int s[])
{ int popped_element;
if(top == -1)
{ popped_element = 0;
flag = 0;
}
else
{ flag = 1;
popped_element = s[top];
--top;
}
return (popped_element);
}
/* Definition of the display function */
void display(int s[])
{ int i;
if(top == -1)
printf("n Stack is empty");
else
{ for(i = top; i >= 0; --i)
printf("n %d", s[i] );
}
}

2. /* Function main */
void main()
{ int data;
char choice;
int q = 0;
int top = -1;
clrscr();
do
{ printf(" n enter i to insert");
printf(" n enter p to delete");
printf(" n enter q to quit");
printf("n enter your choice : ");
do
{ choice = getchar();
choice =tolower(choice);
}while(strchr("ipq",choice)==NULL);
switch(choice)
{
case 'i' : printf("n Input the element to push:");
scanf("%d", &data);
push(stack, data);
if(flag)
{ printf("n After inserting ");
display(stack);
if(top == (size-1))
printf("n Stack is full");
}
else printf("n Stack overflow after pushing");
break;
case 'p' : data = pop(stack);
if(flag)
{ printf("n Data is popped: %d", data);
printf("n Rest data in stack is as follows:n");
display(stack);
}
else printf("n Stack underflow" );
break;
case 'q': q = 1;
}
} while(!q);
}

3. /* THIS PROGRAM DEMONSTRATES THE STACK OPERATIONS USING OOPS-
CLASS STACK*/
/* cstack.cpp */
#include<iostream.h>
#include<conio.h>
#include<stdio.h>
class stack
{ int stack[30];
int top,n;
public:
stack()
{ top=-1; //indicates stack is empty
n=5;
}
void push(int);
int pop();
void display();
};
void stack::push(int x)
{ if(top<n)
{ top++;
stack[top]=x;
}
else cout<<"n the stack is full";
}
int stack::pop()
{ int v=-99;
if(top>=0)
{ v=stack[top];
top--;
}
return v;
}
void stack::display()
{ int i;
if(top>=0)
{ for(i=top;i>=0;i--)
cout<<stack[i]<<" ";
}
else cout<<"n stack is empty";
}
void main()
{ stack s;
char ch; int x;
clrscr();
do
{ cout<<"n enter i to insert an element";
cout<<"n enter d to view the contents";
cout<<"n enter r to remove an element";

4. cout<<"n enter q to quit";
cout<<"n enter your choice : ";
cin>>ch;
switch(ch)
{ case 'i': cout<<"n enter the value to insert";
cin>>x;
s.push(x);
break;
case 'd': cout<<"n";
s.display();
break;
case 'r': x=s.pop();
if(x==-99) cout<<"n stack is empty";
else cout<<" n the element removed is "<<x;
break;
}
}while(ch!='q');
}
OUTPUT:
enter i to insert an element
enter d to view the contents
enter r to remove an element
enter q to quit
enter your choice : r
stack is empty
enter i to insert an element
enter d to view the contents
enter r to remove an element
enter q to quit
enter your choice : i
enter the value to insert : 1
enter i to insert an element
enter d to view the contents
enter r to remove an element
enter q to quit
enter your choice : i
enter the value to insert : 2
enter i to insert an element
enter d to view the contents
enter r to remove an element
enter q to quit
enter your choice : i
enter the value to insert : -1

5. enter i to insert an element
enter d to view the contents
enter r to remove an element
enter q to quit
enter your choice : d
-1 2 1
enter the value to insert : 2
enter i to insert an element
enter d to view the contents
enter r to remove an element
enter q to quit
enter your choice : i
enter the value to insert : -1
enter i to insert an element
enter d to view the contents
enter r to remove an element
enter q to quit
enter your choice : d
-1 2 1
enter i to insert an element
enter d to view the contents
enter r to remove an element
enter q to quit
enter your choice : r
the element removed is -1
enter i to insert an element
enter d to view the contents
enter r to remove an element
enter q to quit
enter your choice : r
the element removed is 2
enter i to insert an element
enter d to view the contents
enter r to remove an element
enter q to quit
enter your choice : r
the element removed is 1
enter i to insert an element
enter d to view the contents
enter r to remove an element
enter q to quit
enter your choice : r
stack is empty

6. /*THE FOLLOWING PROGRAM CONVERTS ANY infix EXPRESSION TO POSTFIX
postfix.c */
#include<iostream.h>
#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
#include<ctype.h>
#include<string.h>
int precedence(char op)
{
switch(op)
{
case '-':return 1;
case '+':return 1;
case '*':return 2;
case '/':return 2;
case '$':return 3;
case '(':return 0;
}
return -1;
}
void push(char a[],int *top,char ch)
{ a[*top]=ch;
(*top)++;
}
char pop(char a[],int *top)
{ *top=*top-1;
return a[*top];
}
void main()
{
int top=0,i=0,j=0,k,l,length=0;
char stack[50],infix[50],postfix[50];
char ch;
clrscr();
cout<<"Enter the infix expression : n";
scanf("%s",infix);
length=strlen(infix);
for(i=0;i<length;i++)
{
if(infix[i]=='(')
push(stack,&top,infix[i]);
if(isalpha(infix[i]))
{ postfix[j]=infix[i];
j++;
}

7. if(infix[i]==')')
{ while(stack[top-1]!='(')
{ postfix[j]=pop(stack,&top);
j++;
}
pop(stack,&top);
}
if(infix[i]=='+'||infix[i]=='-'||infix[i]=='/'||infix[i]=='*'||infix[i]=='$')
{ if(precedence(stack[top-1])<precedence(infix[i]))
push(stack,&top,infix[i]);
else
{ while(precedence(stack[top-1])>=precedence(infix[i]))
{ postfix[j]=pop(stack,&top);
j++;
}
push(stack,&top,infix[i]);
}
}
}
while(top!=0)
{ postfix[j]=pop(stack,&top);
j++;
}
cout<<"nThe postfix expression is :n";
for(k=0;k<j;k++)
cout<<postfix[k];
getch();
}
OUTPUT:
Enter the infix expression :
(((X*Y-A*B)-D/F)+A)*B
The postfix expression is :
XY*AB*-DF/-A+B*
do you want to continue (y/n) : y
Enter the infix expression :
A*B-P/(Q*(A-C+P*D)/B)
The postfix expression is :
AB*PQAC-PD*+*B//-
do you want to continue (y/n) : n

8. /* INSERTION AND DELETION IN A QUEUE ARRAY IMPLEMENTATION */
/* queue_a.c */
# include<stdio.h>
# include<string.h>
# include<ctype.h>
# include<stdlib.h>
# define size 5
int ch;
int q[size];
int rear = 0;
int front = 0;
void Insert_queue();
void Delete_queue();
void Display_queue();
/* Function to create queue */
void Insert_queue()
{ printf("n Input the element :");
scanf("%d", &ch);
if(rear < size)
{ rear ++;
q[rear] = ch ;
if(front == 0)
front = 1;
}
else printf("n Queue is overflow");
}
/* Function to perform delete operation */
void Delete_queue()
{ if (front == 0)
{ printf("n Underflow");
return ;
}
else
{ ch = q[front];
printf("n Element deleted : %d", ch);
}
if(front == rear)
{ front = 0;
rear = 0;
}
else front = front + 1;
}

9. /* Output function */
void Display_queue() //char q[])
{ int i;
if (front == 0)
return;
for(i = front ; i <= rear; i++)
printf(" %d ", q[i]);
}
/* Function main */
void main()
{
int k = 0;
char choice;
clrscr();
do
{ printf("nInsert->i Delete->d Quit->q:");
printf("nInput the choice : ");
do
{ choice = getchar();
choice = tolower(choice);
}while(strchr("idq",choice)==NULL);
switch(choice)
{
case 'i' : Insert_queue();
printf("n Queue after inserting ");
Display_queue();
break;
case 'd' : Delete_queue();
printf("n Queue after deleting:n");
Display_queue();
break;
case 'q': k = 1;
}
} while(!k);
}

10. /* THIS PROGRAM DEMONSTRATES OPERATIONS ON A CIRCULAR QUEUE
USING OOPS-CLASS QUEUE –cqueue.cpp*/
#include<iostream.h>
#include<conio.h>
#include<stdio.h>
class queue
{ int q[30]; //queue declaration
int f,r ;
int n;
public:
queue() //constructor
{ f=r=0; //indicates queue is empty
n=5;
}
void insert(int);
int delet();
void display();
};
void queue::insert(int x)
{ if((r+1)%n==f)
cout<<"n the queue is full";
else
{ r=(r+1)%n;
q[r]=x;
}
}
int queue::delet()
{ int v=-99;
if(f!=r)
{ f=(f+1)%n;
v=q[f];
}
return v;
}
void queue::display()
{ int i;
if(f!=r)
{ i=f;
while(i!=r)
{ i=(i+1)%n;
cout<<q[i]<<" ";
}
}
else cout<<"n queue is empty";
}
void main()
{ queue s;
char ch;int x;
clrscr();
do

11. { cout<<"n enter i to insert an elemnt";
cout<<"n enter d to view the contents";
cout<<"n enter r to remove an elemnt";
cout<<"n enter q to quit";
cout<<"n enter your choice : ";
cin>>ch;
switch(ch)
{ case 'i': cout<<"n enter the value to insert";
cin>>x;
s.insert(x);
break;
case 'd': cout<<"n";
s.display();
break;
case 'r': x=s.delet();
if(x==-99) cout<<"n queue is empty";
else cout<<" n the element removed is "<<x;
break;
}
}while(ch!='q');
}
OUTPUT :
assume size of queue is 3 integers
Insert->i Delete->d Quit->q:
Input the choice : i
Input the element :1
Queue after inserting 1
Insert->i Delete->d Quit->q:
Input the choice : i
Input the element :2
Queue after inserting 1 2
Insert->i Delete->d Quit->q:
Input the choice : d
Element deleted : 1
Queue after deleting: 2
Insert->i Delete->d Quit->q:
Input the choice : d
Element deleted : 2
Queue after deleting:
queue is empty
Insert->i Delete->d Quit->q:
Input the choice : q

12. /* THIS PROGRAM DEMONSTRATES THE CREATION OF A SIMPLE LINKED LIST
INCORPORATING ALL FUNCTIONS OF INSERTION AND DELETION AT THE
BEGINNING , END AND AFTER ANY PARTICULAR NODE WITH DISPLAY FEATURES */
/* LINKLIST.C */
# include <stdio.h>
# include <malloc.h>
struct link
{ int info;
struct link *next;
};
int i,number;
struct link start, *previous, *new1;
void insertiona(struct link *);
void insertionb(struct link *);
void create_list(struct link *);
void insertione(struct link *);
void display(struct link *);
void delete_nodef(struct link *);
void delete_node(struct link *);
void delete_nodel(struct link *);
/* Function to create a linked list */
void create_list(struct link *node)
{ char ch;
start.next = NULL; /* Empty list */
node = &start; /* Point to the start of the list */
i = 0;
printf("n Input choice n for break: ");
ch = getchar();
while(ch != 'n')
{
node->next = (struct link* ) malloc(sizeof(struct link));
node = node->next;
printf("n Input the node: %d: ", i+1);
scanf("%d", &node->info);
node->next = NULL;
fflush(stdin);
printf("n Input choice n for break: ");
ch = getchar();
i++;
}
printf("n Total nodes = %d", i);
}
/* Inserting a node after a particular node*/
void insertiona(struct link *node)
{ int ins_node,x;

13. node = start.next;
previous = &start;
printf("n Input value of the nodeafter which you want to insert:");
scanf("%d", &ins_node);
while((node->info!=ins_node)&&(node!=NULL))
node=node->next;
if(node!=NULL)
{ new1 = (struct link* ) malloc(sizeof(struct link));
printf("n enter the new value to be inserted : ");
scanf(" %d",&new1->info);
new1->next = node->next;
node->next = new1;
}
else
printf("n insertion is not possible");
}
/* Display the list */
void display(struct link *node)
{ node = start.next;
while (node)
{ printf(" %d ", node->info);
node = node->next;
printf(" ");
}
}
void main()
{ int c;
struct link *node = (struct link *) malloc(sizeof(struct link));
clrscr();
do
{ printf("n enter 1 to create the list");
printf("n enter 2 to insert a node at the beginning");
printf("n enter 3 to insert a node anywhere");
printf("n enter 4 to append a node ");
printf("n enter 5 to display the list");
printf("n enter 6 to remove a node from beginning");
printf("n enter 7 to remove a node anywhere");
printf("n enter 8 to remove a node from the end");
printf("n enter 9 to quit");
printf("n enter your choice : ");
scanf("%d",&c);
switch(c)
{ case 1 : create_list(node);
printf("n Created list is as follows:n");
display(node);
break;
case 2 : insertionb(node);

14. break;
case 3 : insertiona(node);
break;
case 4 : display(node);
insertione(node);
break;
case 5 : display(node);
break;
case 6 : delete_nodef(node);
break;
case 7 : delete_node(node);
break;
case 8 : delete_nodel(node);
break;
case 9 : exit(0);
}
}while((c>=1)&&(c<=9));
getch();
}
/* Inserting a node at the beginning*/
void insertionb(struct link *node)
{ node = start.next;
previous = &start;
new1 = (struct link* ) malloc(sizeof(struct link));
new1->next = node ;
previous->next = new1;
printf("n Input the fisrt node value: ");
scanf("%d", &new1->info);
}
/* Inserting a node at the end */
void insertione(struct link *node)
{ node = start.next;
previous = &start;
if(node==NULL)
{ printf("n the list is empty to create return ");
return;
}
else
{ while(node->next!=NULL)
node = node->next;
new1 = (struct link* ) malloc(sizeof(struct link));
printf("n Input the value to be inserted at the end : ");
scanf(" %d",&new1->info);
node->next=new1;
new1->next=NULL;
}
}
/* Removing the first node */

15. void delete_nodef(struct link*node)
{ node = start.next;
previous = &start;
if (node == NULL)
printf("n Under flow");
else
{ previous->next = node->next;
free(node);
}
}
/* Removing a node when information is known*/
void delete_node(struct link *node)
{ int node_number = 1;
int del_node;
node = start.next;
previous = &start;
printf("n Input information of a node you want to delete: ");
scanf("%d", &del_node);
while(node)
{ if(node->info == del_node)
{ printf("n Position of the information in the list is : %d", node_number);
previous->next = node->next;
free(node);
break ;
}
else
{ node = node->next;
previous = previous->next;
}
node_number++;
}
}
/* Removing the last node */
void delete_nodel(struct link *node)
{ int node_number = 0;
node = start.next;
previous = &start;
if (node == NULL)
printf("n Underflow");
else
while(node)
{ node = node->next;
previous = previous->next;
node_number ++;
}
node = start.next;
previous = &start;

16. while(node_number != 1)
{ node = node->next;
previous = previous->next;
node_number --;
}
if(node_number == 1)
{ previous->next = node->next;
free(node);
}
}