C Program to implement queue using Linked list

Implement Queue using link list Initially, the list is empty, so both the front and rear pointers are NULL. The insert function creates a new node, puts the new data value in it, appends it to an existing list, and makes the rear pointer point to it. A delete function checks whether the queue is empty, and if not, retrieves the data value of the node pointed to by the front, advances the front, and frees the storage of the node whose data value has been retrieved.
If the above strategy is used for creating a queue with four data values —10, 20, 30, and 40, the queue gets created as shown in Figure

Program C program for implementation of a stack using the linked list
# include <stdio.h>
# include <stdlib.h>
struct node
{
int data;
struct node *link;
};

void insert(struct node **front, struct node **rear, int value)
{
struct node *temp;
temp=(struct node *)malloc(sizeof(struct node));
/* creates new node
using data value
passed as parameter */
if(temp==NULL)
{
printf("No Memory available Errorn");
exit(0);
}
temp->data = value;
temp->link=NULL;
if(*rear == NULL)
{
*rear = temp;
*front = *rear;
}
else
{
(*rear)->link = temp;
*rear = temp;
}
}

void delete(struct node **front, struct node **rear, int *value)
{
struct node *temp;
if((*front == *rear) && (*rear == NULL))
{
printf(" The queue is empty cannot delete Errorn");
exit(0);
}
*value = (*front)->data;
temp = *front;
*front = (*front)->link;
if(*rear == temp)
*rear = (*rear)->link;
free(temp);
}

void main()
{
struct node *front=NULL,*rear = NULL;
int n,value;
do
{
do
{
printf("Enter the element to be insertedn");
scanf("%d",&value);
insert(&front,&rear,value);
printf("Enter 1 to continuen");
scanf("%d",&n);
} while(n == 1);

printf("Enter 1 to delete an elementn");
scanf("%d",&n);
while( n == 1)
{
delete(&front,&rear,&value);
printf("The value deleted is %dn",value);
printf("Enter 1 to delete an elementn");
scanf("%d",&n);
}
printf("Enter 1 to continuen");
scanf("%d",&n);
} while(n == 1);
}
Output
Enter the element to be inserted
10
Enter 1 to continue
1
Enter the element to be inserted
20
Enter 1 to continue
1
Enter the element to be inserted
30
Enter 1 to continue
0
Enter 1 to delete an element
1
The value deleted is 10
Enter 1 to delete an element
1
The value deleted is 20
Enter 1 to delete an element
0
Enter 1 to continue
1
Enter the element to be inserted
40
Enter 1 to continue
1
Enter the element to be inserted
50
Enter 1 to continue
0
Enter 1 to delete an element
1
The value deleted is 30
Enter 1 to pop an element
1
The value deleted is 40
Enter 1 to delete an element
1
The value deleted is 50
Enter 1 to delete an element
1
The queue is empty, cannot delete Error

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