Queue ADT

Queue ADT

#include<stdio.h>

int q[20],front=-1,rear=-1;
void enqueue()
{
int item;
if(rear<max-1)
{
printf("Enter the element\n");
scanf("%d",&item);
if(rear==-1)
{
front=0;
rear=0;
q[rear]=item;
}
else
q[++rear]=item;
}
else
printf("Overflow\n");
}

void dequeue()
{
if(front>=0)
{
printf("The deleted item =%d",q[front]);
if(front==rear)
{
front=-1;
rear=-1;
}
else
front++;
}
else
printf("Underflow\n");
}

void display()
{
int i;
if((front==-1)&&(rear==-1))
printf("The queue is empty\n");
else
{
printf("The elements of the queue are :\n");
for(i=front;i<=rear;i++)
printf("%d\t",q[i]);
}
}


void main()
{
int ch,item;
printf("\n\tMENU\n1.ENQUEUE\n2.DEQUEUE\n3.DISPLAY\n4.EXIT\n");
while(1)
{
printf("\nEnter your choice\n");
scanf("%d",&ch);
switch(ch)
{
case 1:
enqueue();
break;

case 2:
dequeue();
break;

case 3:
display();
break;

case 4:
exit(0);

default:
printf("Invalid choice\n");
break;
}
}
}