Inserting and deleting an element from the queue using c.

Inserting and deleting an element from the queue using c.

#include <stdio.h>
#include<stdlib.h>
int max=100;
int queue_array[100];
int rear = - 1;
int front = - 1;

void insert()
{
      int add_item;
      if(rear == (max - 1))
      {
    printf("Queue Overflow \n");
      }
      else
      {
    if (front == - 1)
  front = 0;
    printf("\nEnter element : ");
    scanf("%d", &add_item);
    rear = rear + 1;
    queue_array[rear] = add_item;
      }
}
void del()
{
      if (front == - 1 || front > rear)
      {
    printf("Queue Underflow \n");
      }
      else
      {
    printf("\nElement deleted from queue is : %d", queue_array[front]);
    front = front + 1;
      }
}
void display()
{
      int i;
      if (front == - 1)
    printf("Queue is empty \n");
      else
      {
    printf("\nQueue is : ");
    for (i = front; i <= rear; i++)
  printf("%d ", queue_array[i]);
      }
}
void main()
{
      printf("Perform operations on queue");
     printf("\n*******************************\n");
       printf("*     1. Insert element       *\n");
       printf("*     2. Delete element       *\n");
       printf("*     4. Exit                 *\n");
       printf("*******************************");
      int ch;
      while (1)
      {
    printf("\n<<   Choose operation :   >>  ");
    scanf("%d", &ch);
    switch(ch)
    {
  case 1:
insert();
display();
break;
  case 2:
del();
display();
break;
  case 3:
exit(1);
  default:
printf("Invalid operation \n");
    }
      }
}

Output: