libgomp/testsuite/libgomp.c/omp_hello.c

   1 /******************************************************************************
   2 * FILE: omp_hello.c
   3 * DESCRIPTION:
   4 *   OpenMP Example - Hello World - C/C++ Version
   5 *   In this simple example, the master thread forks a parallel region.
   6 *   All threads in the team obtain their unique thread number and print it.
   7 *   The master thread only prints the total number of threads.  Two OpenMP
   8 *   library routines are used to obtain the number of threads and each
   9 *   thread's number.
  10 * AUTHOR: Blaise Barney  5/99
  11 * LAST REVISED: 04/06/05
  12 ******************************************************************************/
  13 #include <omp.h>
  14 #include <stdio.h>
  15 #include <stdlib.h>
  16
  17 int main (int argc, char *argv[]) {
  18
  19 int nthreads, tid;
  20
  21 /* Fork a team of threads giving them their own copies of variables */
  22 #pragma omp parallel private(nthreads, tid)
  23   {
  24
  25   /* Obtain thread number */
  26   tid = omp_get_thread_num();
  27   printf("Hello World from thread = %d\n", tid);
  28
  29   /* Only master thread does this */
  30   if (tid == 0)
  31     {
  32     nthreads = omp_get_num_threads();
  33     printf("Number of threads = %d\n", nthreads);
  34     }
  35
  36   }  /* All threads join master thread and disband */
  37
  38   return 0;
  39 }