Program 10 - Linear Queue

	#include <stdio.h>
	#define MAX 10
	int Q[MAX];
	int f = -1, r = -1;
	void enqueue(int num){
	if(r == MAX -1){
	printf("Queue Overflow\n");
	} else {
	r++;
	Q[r] = num;
	if(f == -1){
	f = 0;
	}
	}
	}
	int dequeue(){
	if(f == -1 || f > r){
	return -1;
	} else {
	return Q[f++];
	}
	}
	void create(){
	int data;
	printf("Enter data: ");
	scanf("%d", &data);
	while(data != -1){
	enqueue(data);
	printf("Enter data or enter -1 to stop: ");
	scanf("%d", &data);
	}
	}
	void display(){
	int i;
	if(f == -1 || f > r){
	printf("Queue Empty\n");
	} else {
	for(i = f; i <= r; i++){
	printf("%d ", Q[i]);
	}
	printf("\n");
	}
	}
	int main(){
	int choice, num, rpt = 1;
	printf("***Create Linear Queue***\n");
	create();
	while(rpt != 0){
	printf("1. Enqueue\n2. Dequeue\n3. Display\n4. Exit\n");
	printf("----------------\n");
	printf("Enter a choice: ");
	scanf("%d", &choice);
	switch(choice){
	case 1:
	printf("Enter a num: ");
	scanf("%d", &num);
	enqueue(num);
	break;
	case 2:
	num = dequeue();
	if(num != -1){
	printf("%d successfully deleted\n", num);
	} else {
	printf("Queue Underflow\n");
	}
	break;
	case 3:
	display();
	break;
	case 4:
	exit(0);
	}
	printf("Do you want to continue? (1/0): ");
	scanf("%d", &rpt);
	system("cls");
	}
	}