#include <stdio.h> 
#include <pthread.h> 
#include <unistd.h> 
int this_is_global;
void thread_func( void *ptr );

 int main( ) 
{
int local_main; int pid, status; 
pthread_t thread1, thread2;
printf("First, we create two threads to see better what context they share...\n");
this_is_global=1000; 
printf("Set this_is_global=%d\n",this_is_global);

pthread_create( &thread1, NULL, (void*)&thread_func, (void*) NULL); pthread_create(&thread2, NULL, (void*)&thread_func, (void*) NULL); pthread_join(thread1, NULL); pthread_join(thread2, NULL); 

printf("After threads, this_is_global=%d\n",this_is_global);
printf("\n"); 
printf("Now that the threads are done, let's call fork..\n"); 
local_main=17; this_is_global=17; 

printf("Before fork(), local_main=%d, this_is_global=%d\n",local_main, this_is_global); 

pid=fork();
 if (pid == 0) 
{ 
	/* this is the child */ 
	printf("In child, pid %d: &global: %X, &local: %X\n", getpid(), 			
		&this_is_global, &local_main); 

	local_main=13; this_is_global=23;

	printf("Child set local main=%d, this_is_global=%d\n",local_main, 			this_is_global);
 	exit(0); 
} 

else 
{
	 /* this is parent */ 
	printf("In parent, pid %d: &global: %X, &local: %X\n", getpid(), 	&this_is_global, &local_main);
	wait(&status);
	 printf("In parent, local_main=%d, this_is_global=%d\n",local_main, 	this_is_global);
} 

exit(0); } 
void thread_func(void *dummy) 
{
	 int local_thread; 
	printf("Thread %d, pid %d, addresses: &global: %X, &local: %X\n", 	pthread_self(),getpid(),&this_is_global, &local_thread);

	this_is_global++;
	printf("In Thread %d, incremented this_is_global=%d\n", pthread_self(), 	this_is_global);
 	pthread_exit(0); 

}