C Program for Queue using array

Program:-

/* Queue implementation using array*/
#include<stdio.h>
#include<process.h>
# define MAX 5

int queue[MAX];
int rear = -1;
int front = -1;
void insert();
void del();
void display();
void main()
{
int choice;

while(1)
{
printf("1.Insert\n");
printf("2.Delete\n");
printf("3.Display\n");
printf("4.Quit\n");
printf("Enter your choice : ");
scanf("%d",&choice);

switch(choice)
{
case 1 :
insert();
break;
case 2 :
del();
break;
case 3:
display();
break;
case 4:
exit(1);
default:
printf("Enter correct choice\n");
}/*End of switch*/
}/*End of while*/
}/*End of main()*/

void insert()
{
int ele;
if (rear==MAX-1)
printf("Queue Overflow\n");
else
{
if (front==-1)  /*If queue is initially empty */
front=0;
printf("Enter an element : ");
scanf("%d", &ele);
rear=rear+1;
queue[rear] = ele ;
}
}/*End of insert()*/

void del()
{
if (front == -1)
printf("Queue Underflow\n");
else
{
printf("Element deleted from queue is : %d\n", queue[front]);
front=front+1;
if(front>rear)
{
printf("\nQueue is empty\n");
front=rear=-1;
}
}
}/*End of del() */

void display()
{
int i;
if (front == -1)
printf("Queue is empty\n");
else
{
printf("\nQueue is :\n");
for(i=front;i<= rear;i++)
printf("%d  ",queue[i]);
printf("\n");
}
}/*End of display() */


Output:-



1.Insert
2.Delete
3.Display
4.Quit
Enter your choice : 1
Enter an element : 10
1.Insert
2.Delete
3.Display
4.Quit
Enter your choice : 1
Enter an element : 20
1.Insert
2.Delete
3.Display
4.Quit
Enter your choice : 1
Enter an element : 30
1.Insert
2.Delete
3.Display
4.Quit
Enter your choice : 3

Queue is :
10  20  30
1.Insert
2.Delete
3.Display
4.Quit
Enter your choice : 2
Element deleted from queue is : 10
1.Insert
2.Delete
3.Display
4.Quit
Enter your choice : 3

Queue is :
20  30
1.Insert
2.Delete
3.Display
4.Quit
Enter your choice : 4