Code:
#include stdio.h
#include stdlib.h
#define MAX 10
struct node
{
int data;
struct node *link;
}*front, *rear;
// function protypes
void insert();
void delete();
void queue_size();
void check();
void first_element();
void main()
{
int choice, value;
while(1)
{
printf("enter the choice \n");
printf("1 : create an empty queue \n2 : Insert element\n");
printf("3 : Dequeue an element \n4 : Check if empty\n");
printf("5. Get the first element of the queue\n");
printf("6. Get the number of entries in the queue\n");
printf("7. Exit\n");
scanf("%d", &choice);
switch (choice) // menu driven program
{
case 1:
printf("Empty queue is created with a capacity of %d\n", MAX);
break;
case 2:
insert();
break;
case 3:
delete();
break;
case 4:
check();
break;
case 5:
first_element();
break;
case 6:
queue_size();
break;
case 7:
exit(0);
default:
printf("wrong choice\n");
break;
}
}
}
// to insert elements in queue
void insert()
{
struct node *temp;
temp = (struct node*)malloc(sizeof(struct node));
printf("Enter value to be inserted \n");
scanf("%d", &temp->data);
temp->link = NULL;
if (rear == NULL)
{
front = rear = temp;
}
else
{
rear->link = temp;
rear = temp;
}
}
// delete elements from queue
void delete()
{
struct node *temp;
temp = front;
if (front == NULL)
{
printf("queue is empty \n");
front = rear = NULL;
}
else
{
printf("deleted element is %d\n", front->data);
front = front->link;
free(temp);
}
}
// check if queue is empty or not
void check()
{
if (front == NULL)
printf("\nQueue is empty\n");
else
printf("*************** Elements are present in the queue **************\n");
}
// returns first element of queue
void first_element()
{
if (front == NULL)
{
printf("**************** The queue is empty ****************\n");
}
else
printf("**************** The front element is %d ***********\n", front->data);
}
// returns number of entries and displays the elements in queue
void queue_size()
{
struct node *temp;
temp = front;
int cnt = 0;
if (front == NULL)
{
printf(" queue empty \n");
}
while (temp)
{
printf("%d ", temp->data);
temp = temp->link;
cnt++;
}
printf("********* size of queue is %d ******** \n", cnt);
}
Output:
enter the choice
1 : create an empty queue
2 : Insert element
3 : Dequeue an element
4 : Check if empty
5 : Get the first element of the queue
6 : Get the number of entries in the queue
7 : Exit
6
**************Size is 0 ************
enter your choice
1 : create an empty queue
2 : Insert element
3 : Dequeue an element
4 : Check if empty
5 : Get the first element of the queue
6 : Get the number of entries in the queue
7 : Exit
3
queue is empty
enter the choice
1 : create an empty queue
2 : Insert element
3 : Dequeue an element
4 : Check if empty
5 : Get the first element of the queue
6 : Get the number of entries in the queue
7 : Exit
4
queue is empty
enter the choice
1 : create an empty queue
2 : Insert element
3 : Dequeue an element
4 : Check if empty
5 : Get the first element of the queue
6 : Get the number of entries in the queue
7 : Exit
5
****************The queue is empty****************
enter the choice
1 : create an empty queue
2 : Insert element
3 : Dequeue an element
4 : Check if empty
5 : Get the first element of the queue
6 : Get the number of entries in the queue
7 : Exit
2
enter value to insert
45
enter the choice
1 : create an empty queue
2 : Insert element
3 : Dequeue an element
4 : Check if empty
5 : Get the first element of the queue
6 : Get the number of entries in the queue
7 : Exit
2
enter value to insert
56
enter the choice
1 : create an empty queue
2 : Insert element
3 : Dequeue an element
4 : Check if empty
5 : Get the first element of the queue
6 : Get the number of entries in the queue
7 : Exit
2
enter value to insert
67
enter the choice
1 : create an empty queue
2 : Insert element
3 : Dequeue an element
4 : Check if empty
5 : Get the first element of the queue
6 : Get the number of entries in the queue
7 : Exit
2
enter value to insert
78
enter the choice
1 : create an empty queue
2 : Insert element
3 : Dequeue an element
4 : Check if empty
5 : Get the first element of the queue
6 : Get the number of entries in the queue
7 : Exit
2
enter value to insert
89
enter the choice
1 : create an empty queue
2 : Insert element
3 : Dequeue an element
4 : Check if empty
5 : Get the first element of the queue
6 : Get the number of entries in the queue
7 : Exit
6
- 45 -- 56 -- 67 -- 78 -- 89 -
**************Size is 5 ************
enter the choice
1 : create an empty queue
2 : Insert element
3 : Dequeue an element
4 : Check if empty
5 : Get the first element of the queue
6 : Get the number of entries in the queue
7 : Exit
5
****************The front element is 45 ***********
enter the choice
1 : create an empty queue
2 : Insert element
3 : Dequeue an element
4 : Check if empty
5 : Get the first element of the queue
6 : Get the number of entries in the queue
7 : Exit
3
******45 has been removed******
enter the choice
1 : create an empty queue
2 : Insert element
3 : Dequeue an element
4 : Check if empty
5 : Get the first element of the queue
6 : Get the number of entries in the queue
7 : Exit
3
******56 has been removed******
enter the choice
1 : create an empty queue
2 : Insert element
3 : Dequeue an element
4 : Check if empty
5 : Get the first element of the queue
6 : Get the number of entries in the queue
7 : Exit
3
******67 has been removed******
enter the choice
1 : create an empty queue
2 : Insert element
3 : Dequeue an element
4 : Check if empty
5 : Get the first element of the queue
6 : Get the number of entries in the queue
7 : Exit
6
- 78 -- 89 -
**************Size is 2 ************
enter the choice
1 : create an empty queue
2 : Insert element
3 : Dequeue an element
4 : Check if empty
5 : Get the first element of the queue
6 : Get the number of entries in the queue
7 : Exit
3
******78 has been removed******
enter the choice
1 : create an empty queue
2 : Insert element
3 : Dequeue an element
4 : Check if empty
5 : Get the first element of the queue
6 : Get the number of entries in the queue
7 : Exit
3
******89 has been removed******
enter the choice
1 : create an empty queue
2 : Insert element
3 : Dequeue an element
4 : Check if empty
5 : Get the first element of the queue
6 : Get the number of entries in the queue
7 : Exit
6
**************Size is 0 ************
enter the choice
1 : create an empty queue
2 : Insert element
3 : Dequeue an element
4 : Check if empty
5 : Get the first element of the queue
6 : Get the number of entries in the queue
7 : Exit
2
enter value to insert
34
enter the choice
1 : create an empty queue
2 : Insert element
3 : Dequeue an element
4 : Check if empty
5 : Get the first element of the queue
6 : Get the number of entries in the queue
7 : Exit
6
- 34 -
**************Size is 1 ************
enter the choice
1 : create an empty queue
2 : Insert element
3 : Dequeue an element
4 : Check if empty
5 : Get the first element of the queue
6 : Get the number of entries in the queue
7 : Exit
7
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