Queue_02_CQueue

//Circular Queue

#include<conio.h>
#include<stdio.h>
#define MAX 3

//Globar Variable
int queue [MAX];
int front = -1,rear = -1;

//UDF Function
void insert();
int Delete_Element();
void display();

void main()
{
    int op, val;
    clrscr();

    do
    {
        getch();
        clrscr();

        printf("\n -------------------------");
        printf("\n -----Circular Queue------");
        printf("\n -------------------------");
        printf("\n 1. Insert");
        printf("\n 2. Delete");
        printf("\n 3. Display");
        printf("\n 4. Exit");
        printf("\n -------------------------");
        printf("\n Maximum 3 Value Get");
        printf("\n -------------------------");
        printf("\n Enter Choice : ");
        scanf("%d", &op);
        printf(" -------------------------");

        switch(op)
        {
            case 1:
                insert();
            break;

            case 2:
                val=Delete_Element();
                if(val !=-1)
                {
                    printf("\n The Number Delete is : %d", val);
                }
            break;

            case 3:
                display();
            break;
        }
    }while(op != 4);
    getch();
}

//UDF Function Declaration

void insert()
{
    int num;
    printf("\n Enter The Number to be Insert in The Queue : ");
    scanf("%d", &num);

    if(front == 0 && rear == MAX  -1 || front == MAX -1 && rear == front -1)
    {
        printf("\n Circular Queue is Overflow");
        return;
    }
    else
    {
        if(front == -1 && rear == -1)
        {
            front = rear = 0;
            queue[rear]=num;
        }
        else if(rear==MAX-1 && front!=0)
        {
            rear=0;
            queue[rear]=num;
        }
        else
        {
            rear++;
            queue[rear]=num;
        }
    }
}

int Delete_Element()
{
    int val;
    if(front == -1 && rear == -1)
    {
        printf("\n Circular Queue is Underflow");
        return -1;
    }

    val = queue [front];

    if(front == rear)
    {
        front = rear = -1;
    }
    else
    {
        if(front == MAX -1)
        {
            front=0;
        }
        else
        {
            front++;
        }
    }
    return val;
}

void display()
{
    int i;
    printf("\n ");
    if(front == -1 && rear == -1)
    {
        printf("\n Circular Queue is Empty");
    }
    else
    {
        if(rear>=front)
        {
            for(i=front; i<=rear; i++)
            {
                printf("\n Element : %d", i);
                printf(" -> %d", queue[i]);
            }
        }
        else
        {
            for (i=front; i<MAX; i++)
            {
                printf("\n Element : %d", i);
                printf(" -> %d", queue[i]);
            }

            for (i=0; i<rear; i++)
            {
                printf("\n Element : %d", i);
                printf(" -> %d", queue[i]);
            }
        }
    }
}