in the above program i have just created 2 threads and passed thr1 ( = 1 ) and thr2 ( = 2 ) values as parameters the function void * thread ( void * ptr ) is executes as a separate thread, we create two thread objects thread1 and thread2, and start threads using pthread_create function passing thread object, function pointer and parameters as arguments, here NULL specifies default attributes for the thread, we can change this by passing pthread_attr_t structure instead of NULL.
we wait for the threads to finish using the pthread_join function
One major problem that is faced by most of the people is of using a library which is not a thread safe library, so you need to be careful about the libraries you use in your program, if not sure about a particular library being thread safe, just assume it not to be thread safe

PS – No updates from a long time as i dont have a proper net connection ….