A5

#include<stdio.h>

#include<pthread.h>

#include<semaphore.h>

#include<stdlib.h>

#include<unistd.h>

sem_t mutex,writeblock;

long int data=0,rcount=0;

void *reader(void *arg)

{int f;

f=((long int)arg);

sem_wait(&mutex);

rcount=rcount+1;

if(rcount==1)

sem_wait(&writeblock);

sem_post(&mutex);

printf("data read by the reader %d id %ld\n",f,data);

sleep(1);

sem_wait(&mutex);

rcount=rcount-1;

if(rcount==0)

sem_post(&writeblock);

sem_post(&mutex);

}

void *writer(void *arg)

{int f;

f=((long int)arg);

sem_wait(&writeblock);

data++;

printf("data written by the writer %d id %ld\n",f,data);

sleep(1);

sem_post(&writeblock);

}

int main()

{

 long int i;

int b,pr;

pthread_t rtid[10],wtid[10];

sem_init(&mutex,0,1);

sem_init(&writeblock,0,1);

printf("enter no of process you want to create==");

scanf("%d",&pr);

for(i=0;i<=pr;i++)

{

pthread_create(&wtid[i],NULL,writer,(void*)(long)i);

pthread_create(&rtid[i],NULL,reader,(void*)(long)i);

}

for(i=0;i<=pr;i++)

{

pthread_join(wtid[i],NULL);

pthread_join(rtid[i],NULL);

}}

/*