C Program to perform Insertion and Deletion operation in Queue

Queue is a linear data structure, in which the first data element inserted from one end called REAR (also called tail),and the deletion of exisiting element takes place from the other end called FRONT(also called head). This make queue is FIFO data structure,which means that element inserted first will also be removed first.We can perform various operation on queue ,here we provide a simple C program which perform insertion and deletion operation.

Example of C Program to perform Insertion and Deletion operation in Queue

#include < stdio.h>
#include < conio.h>
#include < malloc.h> 
#define SIZE 5
void menu();
void display();
int underflow();
int overflow();
void enqueue(int);
void dequeue();
int queue[SIZE];
int front=-1;
int rear=-1;
void main()
{
    clrscr();
    menu();
}
void menu()
{
    int choice,item;
    printf("MENU");
    printf("n1. Insert into the queue");
    printf("n2. Delete from queue");
    printf("n3. Display");
    printf("n4. Exit");
    printf("nEnter your choice: ");
    scanf("%d",&choice);
    switch(choice)
    {
        case 1:
            clrscr();
            if(overflow()==0)
            {
                printf("nEnter the item tobe inserted: ");
                scanf("%d",&item);
                enqueue(item);
                clrscr();
                printf("nAfter inserting queue is:n");
            }
            display();
            getch();
            clrscr();
            menu();
            break;
        
case 2:
            clrscr();
            if(underflow()==1)
            {
                dequeue();
                if(underflow()==1)
                {
                    printf("nAfter deletion queue is:n");
                    display();
                }
            }
            getch();
            clrscr();
            menu();
            break;
        case 3:
            clrscr();
            if(underflow()==1)
            {
                printf("The queue is:n");
                display();
            }
            getch();
            clrscr();
            menu();
            break;
        case 4:
            exit(1);
        default:
            clrscr();
            printf("Your choice is wrongnn");
            menu();
    }
}
int underflow()
{
    if((front==-1)&&(rear==-1))
    {
        printf("nQueue is empty");
        return(0);
    }
    else
    {
        return(1);
    }
}

int overflow()
{
    if(rear==SIZE-1)
    {
        printf("nQueue is fulln");
        return(1);
    }
    else
    {
        return(0);
    }
}
void enqueue(int item)
{
    if((front==-1)&&(rear==-1))
    {
        front=0;
        rear=0;
    }
    else
    {
        rear=rear+1;
    }
    queue[rear]=item;
}
void dequeue()
{
    if(front==rear)
    {
        front=-1;
        rear=-1;
    }
    else
    {
        front=front+1;
    }
}
void display()
{
    int i;
    for(i=front;i<=rear;i++)
    {
        printf("nElement %d : %d",i+1,queue[i]);
    }
}

Output