readers writers problem.cpp

#include<stdio.h>
#include<conio.h>
#include<stdbool.h>


struct semaphore{
	int mutex;
	int reader_count;
	int reader_wait;
	bool wrt;
};

void addReader(struct semaphore *s){

	if (s->mutex == 0 && s->reader_count == 0){

		printf("\nSorry, File open in Write mode.\nNew Reader is added to queue.\n");
		s->reader_wait++;

	}else{

		printf("\nReader Process added.\n");
		s->reader_count++;
		s->mutex--;
	}
	return ;
}

void addWriter(struct semaphore *s){

	if(s->mutex==1){
		s->mutex--;
		s->wrt=1;
		printf("\nWriter Process added.\n");
	}else if{

		(s->wrt) printf("\nSorry, Writer is already operational.\n");
	}

	elseprintf("\nSorry, File open in Read mode.\n");
	return ;
}

void removeReader(struct semaphore *s){

	if{
		(s->reader_count == 0) printf("\nNo readers to remove.\n");
	}else{

		printf("\nReader Removed.\n");
		s->reader_count--;
		s->mutex++;
	}
	return ;
}

void removeWriter(struct semaphore *s){
	if{
		(s->wrt==0) printf("\nNo Writer to Remove");
	}else{

		printf("\nWriter Removed\n");
		s->mutex++;
		s->wrt=0;
		if(s->reader_wait!=0){

			s->mutex-=s->reader_wait;
			s->reader_count=s->reader_wait;
			s->reader_wait=0;
			printf("%d waiting Readers Added.",s->reader_count);
		}
	}
}

int main(){

	struct semaphore S1={1,0,0};
	while(1){

		system("cls");
		printf("Options :-\n1.Add Reader.\n2.Add Writer.\n3.Remove Reader.\n4.Remove Writer.\n5.Exit.\n\n\tChoice : ");
		intch;
		scanf("%d",&ch);
		switch(ch){

			case 1: addReader(&S1); break;

			case 2: addWriter(&S1); break;

			case 3: removeReader(&S1); break;

			case 4: removeWriter(&S1); break;

			case 5: printf("\n\tGoodBye"); getch(); return 0;

			default: printf("\nInvalid Entry"); continue;

		}

		printf("\n\n<<<<<< Current Status >>>>>>\n\n\tMutex\t\t:\t%d\n\tActive Readers\t:\t%d\n\tWaiting Readers\t:\t%d\n\tWriter Active\t:\t%s\n\n", S1.mutex, S1.reader_count, S1.reader_wait, (S1.mutex==0 && S1.reader_count==0) ? "YES" : "NO");
		system("pause");

	}
}