OpenMP编译执行

Question

I'm using linux and I don't know which is the command line to compile an OpenMP file, can I simply write:

g++ myprog.cpp -o myprog

or g++ compiler doesn't work?

And how I execute myprog ? Where I choose the number of threads?

Answer 1

You want to compile with -fopenmp and before you run the executable, set the OMP_NUM_THREADS variable to set the number of threads, for example with export in bash. An example from here :

$ 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