linear queue.c

#include<stdio.h>
#define SIZE 5

void enQueue(int);
void deQueue();
void display();

int queue[SIZE], front = -1, rear = -1;

int main()
{
   int value, choice;

   while(1){
      printf("\n\n***** MENU *****\n");
      printf("1. Insertion\n2. Deletion\n3. Display\n4. Exit");
      printf("\nEnter your choice: ");
      scanf("%d",&choice);
      switch(choice){
	 case 1: printf("Enter the value to be insert: ");
		 scanf("%d",&value);
		 enQueue(value);
		 break;
	 case 2: deQueue();
		 break;
	 case 3: display();
		 break;
		  case 4: exit(0);
	 default: printf("\nWrong selection!!! Try again!!!");
      }
     
   }
   return 0;

}
void enQueue(int value){
   if(rear == SIZE-1)
      printf("\nQueue is Full!!! Insertion is not possible!!!");
   else{
      if(front == -1)
	 front = 0;
      rear++;
      queue[rear] = value;
      printf("\nInsertion success!!!");
   }
}
void deQueue(){
   if(front == -1 && rear == -1)
   {
   
      printf("\nQueue is underflow ");
  }
      else if(front == rear)
      {
      	printf("\nDeleted : %d", queue[front]);
        front = rear = -1;
      	
	  }
   else{
      printf("\nDeleted : %d", queue[front]);
      front++;
      
   }
}
void display(){
   if(rear == -1)
      printf("\nQueue is Empty!!!");
   else{
      int i;
      printf("\nQueue elements are:\n");
      for(i=front; i<=rear; i++)
	  printf("%d\t",queue[i]);
   }

}