Thread Return Values

• If the second argument you pass to pthread_join is non-null, the thread's return value will be placed in the location pointed to by that argument.
• The thread return value, like the thread argument, is of type void*.
• The following program (see Fig. 4) computes the $n^{th}$ prime number in a separate thread. That thread returns the desired prime number as its thread return value. http://siber.cankaya.edu.tr/SystemsProgramming/cfiles/primes.cprimes.c

  Figure 4: Compute Prime Numbers in a Thread

  
• The pthread_self function returns the thread ID of the thread in which it is called. This thread ID may be compared with another thread ID using the pthread_equal function.

  if (!pthread_equal (pthread_self (), other_thread)) 
  pthread_join (other_thread, NULL);