OpenMP set_num_threads() is not working

Question

I am writing a parallel program using OpenMP in C++.

I want to control the number of threads in the program using omp_set_num_threads(), but it does not

Answer 1

Try setting your num_threads inside your omp parallel code, it worked for me. This will give output as 4

#pragma omp parallel
{
   omp_set_num_threads(4);
   int id = omp_get_num_threads();
   #pragma omp for
   for (i = 0:n){foo(A);}
}

printf("Number of threads: %d", id);