OpenMP- Hello world!

Hello world!

Let's print the statement "Hello world!" using all the threads. Here the variable tid gives your thread id. Our server has only two threads. Threfore, the Hello world! will be printed twice.

#include <omp.h>
#include <stdio.h>

 main(int argc, char *argv[]) {

 int nthreads, tid;

 /* Fork a team of threads with each thread having a private tid variable */
 #pragma omp parallel private(tid)
   {

   /* Obtain and print thread id */
   tid = omp_get_thread_num();
   printf("Hello World! from thread = %d\n", tid);

   /* Only master thread does this */
   if (tid == 0) 
     {
     nthreads = omp_get_num_threads();
     printf("Number of threads = %d\n", nthreads);
     }

   }  /* All threads join master thread and terminate */

 }

c++

To compile in your computer this code, run the following:

gcc -o omp_helloc -fopenmp omp_hello.c
$ export OMP_NUM_THREADS=2
$ ./omp_helloc
Hello World from thread = 0
Hello World from thread = 1
Number of threads = 2

Note that the environment variable OMP_NUM_THREADS was used to specify number of threads.

OpenMP- Hello world!

Hello world!

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OpenMP- Hello world!

Hello world!

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