Circular Queue.c

#include<stdio.h>
#include<stdlib.h>
#define n MAX_SIZE
int MAX_SIZE=10;
int cq[n];
int first=-1;
int last=-1;

void second(void)
{
	system("cls"); //For Windows
	// clrscr(); //For Mac/Linux
	printf("\n=====================================================================================================================================");
	printf("\n\t\t\t\t    __  ___           __      __                   __   __  __ ___ __ __  __   __  ___");
	printf("\n\t\t\t\t|_/|__)| | ||_/   /\\ / _  /\\ |__)|  | /\\ |     /| (__\\ |__)|__) | /  (_  /  \\ /__    /");
	printf("\n\t\t\t\t| \\| \\ | | || \\  /--\\\\__)/--\\| \\ |/\\|/--\\|__    |  __/ |__)|__) | \\____) \\__/ \\__)  / ");
	printf("\n=====================================================================================================================================\n");
}

void ins()
{
	int x,item;
	if((first==0 && last==n-1) || (first==last+1))
	{
		printf("\n\t\t\t\tQueue Overflow!!\n");
		return;
	}
	printf("\n\t\t\t\tHow many elements do you want to insert now? Note: Max Size Available is %d",n);
	scanf("%d",&x);
	for(int i=1;i<=x;i++)
	{
		printf("\n\t\t\t\tInput the element for insertion in queue at pos %d : ",i);
		scanf("%d", &item);
		if(first==-1)
		{
			first=0;
			last=0;
		}
		else
		{
			if(last==n-1)
				last=0;
			else
				last+=1;
		}
		cq[last]=item;
	}
}

void del()
{
	int x;
	if(first==-1)
	{
		printf("\n\t\t\t\tQueue Underflow!!\n");
		return ;
	}
	printf("\n\t\t\t\tHow many elements do you want to delete?: ");
	scanf("%d",&x);
	printf("\n\t\t\t\tElement deleted from queue : ");
	for(int i=1;i<=x;i++)
	{
		printf(" %d ",cq[first]);
		if(first==last)
		{
			first=-1;
			last=-1;
		}
		else
		{
			if(first==n-1)
				first=0;
			else
				first+=1;
		}
	}
}

void disp()
{
	int first_pos=first,last_pos=last;
	if(first==-1)
	{
		printf("\n\t\t\t\tQueue is empty!!\n");
		return;
	}
	printf("\n\t\t\t\tQueue elements:: ");
	if(first_pos<=last_pos)
	{
		while(first_pos<=last_pos)
		{
			printf(" %d ",cq[first_pos]);
			first_pos++;
		}
	}
	else
	{
		while(first_pos<=n-1)
		{
			printf(" %d ",cq[first_pos]);
			first_pos++;
		}
		first_pos=0;
		while(first_pos<=last_pos)
		{
			printf(" %d ",cq[first_pos]);
			first_pos++;
		}
	}
	printf("\n");
}

void main()
{
	int choice,a;
	second();
	do
	{
		printf("\n\t\t\t\t===============Circular Queue Operation===============\n\n");
		printf("\n\t\t\t\tEnter Max Size of Queue: ");
		scanf("%d",&a);
		n=a;
		printf("\n\t\t\t\tMax Size Alloted to queue: %d",n);
		printf("\n\t\t\t\t1.Insert");
		printf("\n\t\t\t\t2.Delete");
		printf("\n\t\t\t\t3.Display");
		printf("\n\t\t\t\t4.Quit");
		printf("\n\t\t\t\tEnter your choice: ");
		scanf("%d",&choice);
		switch(choice)
		{
			case 1 :
				ins();
				break;
			case 2 :
				del();
				break;
			case 3:
				disp();
				break;
			case 4:
				exit(0);
			default:
				printf("\n\t\t\t\tInvalid choice!!\n");
		}
	}while(choice!=4);
}