DP.c

#include<stdio.h>
#include<stdlib.h>
#include<pthread.h>
#include<semaphore.h>
#include<unistd.h>

sem_t room;
sem_t chopstick[5];

void *philosopher(void *);
void eat(int);

void eat(int phil){
	printf("\nPhilosopher %d is eating",phil);
}

int main() {
	int i,a[5];
	pthread_t tid[5];     
	sem_init(&room,0,4);
	for(i=0;i<5;i++)        
		sem_init(&chopstick[i],0,1); 
		
	for(i=0;i<5;i++){
		a[i]=i;
		pthread_create(&tid[i],NULL,philosopher,(void *)&a[i]); 
	}
	for(i=0;i<5;i++)
		pthread_join(tid[i],NULL);
}

void *philosopher(void *num) {
	int phil=*(int *)num;
	sem_wait(&room); 
	printf("\nPhilosopher %d has entered room",phil);
	sem_wait(&chopstick[phil]);
	sem_wait(&chopstick[(phil+1)%5]);
	eat(phil);
	sleep(2);
	printf("\nPhilosopher %d has finished eating",phil);
	sem_post(&chopstick[(phil+1)%5]);
	sem_post(&chopstick[phil]);
	sem_post(&room);
}

/*Philosopher 0 has entered room
Philosopher 1 has entered room
Philosopher 1 is eating
Philosopher 3 has entered room
Philosopher 3 is eating
Philosopher 2 has entered room
Philosopher 1 has finished eating
Philosopher 3 has finished eating
Philosopher 0 is eating
Philosopher 4 has entered room
Philosopher 2 is eating
Philosopher 0 has finished eating
Philosopher 2 has finished eating
Philosopher 4 is eating
Philosopher 4 has finished eating*/