diningphilospher.c

#include<stdio.h>
#include<semaphore.h>
#include<pthread.h>
#define N 5
#define THINKING 0
#define HUNGRY 1
#define EATING 2
#define RIGHT (ph_num+1)%N
#define LEFT (ph_num+4)%N

sem_t mutex;
sem_t S[N];
void * philospher(void *num);
void fork_hunger(int);
void fork_thinking(int);
void fork_eating(int);
int state[N];
int phil_num[N]={0,1,2,3,4};
int main()
{
int i;
pthread_t thread_id[N];
sem_init(&mutex,0,1);
	for(i=0;i<N;i++)
		sem_init(&S[i],0,0);
		for(i=0;i<N;i++)
			{
				pthread_create(&thread_id[i],NULL,philospher,&phil_num[i]);
				printf("Philosopher %d is thinking\n",i+1);

			}
	for(i=0;i<N;i++)
		pthread_join(thread_id[i],NULL);
}
void *philospher(void *num)
{
while(1)
	{
		int *i = num;
		sleep(1);
		fork_hunger(*i);
		sleep(0);
		fork_thinking(*i);
	}
}
void fork_hunger(int ph_num)
{
sem_wait(&mutex);
state[ph_num] = HUNGRY;
printf("Philosopher %d is Hungry\n",ph_num+1);
fork_eating(ph_num);
sem_post(&mutex);
sem_wait(&S[ph_num]);
sleep(1);
}
void fork_eating(int ph_num)
{
if (state[ph_num] == HUNGRY && state[LEFT] != EATING && state[RIGHT] != EATING)
{
	state[ph_num] = EATING;
	sleep(2);
	printf("Philosopher %d takes fork %d and %d\n",ph_num+1,LEFT+1,ph_num+1);//extra
	printf("Philosopher %d is Eating\n",ph_num+1);
	sem_post(&S[ph_num]);
}
}
void fork_thinking(int ph_num)
{
sem_wait(&mutex);
state[ph_num] = THINKING;
printf("Philosopher %d putting fork %d and %d down\n",ph_num+1,LEFT+1,ph_num+1);
printf("Philosopher %d is thinking\n",ph_num+1);
fork_eating(LEFT);//already defined
fork_eating(RIGHT);
sem_post(&mutex);
}