Develop a ‘C’ program to create and implement a QUEUE using linked lists.

 

DATA STRUCTURE & ALGORITHM USING C – LAB (2018407)

 UNIT – 06

Develop a ‘C’ program to create and implement a QUEUE using linked lists.

Program:

# include <stdlib.h>
# include <conio.h>
struct queue
{
int data;
struct queue *next;
};
typedef struct queue node;
node *front = NULL;
node *rear = NULL;
node* getnode()
{
node *temp;
temp = (node *) malloc(sizeof(node)) ;
printf("\n Enter data ");
scanf("%d", &temp -> data);
temp -> next = NULL;
return temp;
}
void insertQ()
{
node *newnode;
newnode= getnode();
if(newnode== NULL)
{
printf("\n Queue Full");
return;
}
if(front == NULL)
{
front = newnode;
rear=newnode;
}
else
{
rear -> next = newnode;
rear=newnode;
}
printf("\n\n\t Data Inserted into the Queue..");
}
void deleteQ()
{
node *temp;
if(front == NULL)
{
printf("\n\n\t Empty Queue..");
return;
}
temp = front;
front = front -> next;
printf("\n\n\t Deleted element from queue is %d ", temp -> data);
free(temp);
}
void displayQ()
{
node *temp;
if(front == NULL)
{
printf("\n\n\t\t Empty Queue ");
}
else
{
temp = front;
printf("\n\n\n\t\t Elements in the Queue are: ");
while(temp != NULL)
{
printf("%5d ", temp -> data);
temp = temp -> next;
}
}
}
char menu()
{
char ch;
clrscr();
printf("\n \t..Queue operations using pointers.. ");
printf("\n\t -----------**********-------------\n");
printf("\n 1. Insert ");
printf("\n 2. Delete ");
printf("\n 3. Display");
printf("\n 4. Quit ");
printf("\n Enter your choice: ");
ch = getche();
return ch;
}
void main()
{
char ch;
do
{
ch = menu();
switch(ch)
{
case '1' :
insertQ();
break;
case '2' :
deleteQ();
break;
case '3' :
displayQ();
break;
case '4':
return;
}
getch();
} while(ch != '4');
}