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

void myfunc1(void *ptr);
void myfunc2(void *ptr);

char buf[24];
sem_t mutex;

int main(int argc, char *argv[])
{
 pthread_t thread1;
 pthread_t thread2;

 char *msg1 = "Thread 1";
 char *msg2 = "Thread 2";

 sem_init(&mutex, 0, 1);

 pthread_create (&thread1, NULL, (void *) myfunc1, (void *)msg1);
 pthread_create (&thread2, NULL, (void *) myfunc2, (void *)msg2);

 pthread_join(thread1, NULL);
 pthread_join(thread2, NULL);

 sem_destroy(&mutex);

 return 0;
}

void myfunc1(void *ptr)
{
 char *msg = (char *)ptr;
 printf("%s\n",msg);
 sem_wait(&mutex);
 sprintf(buf,"%s", "Hello There!");
 sem_post(&mutex);
 pthread_exit(0);
}

void myfunc2(void *ptr)
{
 char *msg = (char *)ptr;
 printf("%s\n",msg);
 sem_wait(&mutex);
 printf("%s\n",buf);
 sem_post(&mutex);
 pthread_exit(0);
}