function run in the background c++

Question

I created a function that run in while(1) and return an integer, I want to turn this function in background and recover their return.

who can help me please!

here is my function:

int my_fct() { while(1) { int result = 1; return result; } }

For the sake of readability, you can simplify your function to: int my_fct() { return 1; } — Daniel Daranas
– Daniel Daranas, Commented Nov 11, 2013 at 11:38
You should read something about pthreads. Threads can't be explained in a post. Read: computing.llnl.gov/tutorials/pthreads — anbu selvan
– anbu selvan, Commented Nov 11, 2013 at 11:39
Can you include the function and the code where the function is being called from? And what exactly do you mean bu "turn this function in background"? — Harshil Sharma
– Harshil Sharma, Commented Nov 11, 2013 at 11:41
If you can use c++11, I'd recommend using the built-in threads. Otherwise, pthreads or boost::thread. Just create a thread to do what you need done in the background, and when you need the result, call join() on the thread before trying to use it. — dgel
– dgel, Commented Nov 11, 2013 at 11:44

masoud · Accepted Answer · 2013-11-11 11:44:15Z

3

How about std::async to compute it in a different thread:

int main() { auto r = std::async(std::launch::async, my_fct); int result = r.get(); }

Requires C++11 enabled.

answered Nov 11, 2013 at 11:44

masoud

56.8k18 gold badges152 silver badges214 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

avakar Over a year ago

Note that async might easily get deprecated in C++14: open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3777.pdf

masoud Over a year ago

Interesting, does it have another alternative in C++14?

avakar Over a year ago

None that I know of. The issue is with ~future where it's unclear whether it should block or detach. See open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3773.pdf.

Puppy Over a year ago

It won't be deprecated in C++14. It's too late for such a change. N3777 wasn't even a formal motion in Chicago.

Igor Popov · Accepted Answer · 2013-11-11 12:11:33Z

If you don't have access to C++11 and as you don't have access to pthreads as you are on Windows then you can use OpenMP. Most C++ compilers on both Unix-like systems and Windows support OpenMP. It is easier to use than pthreads. For example your problem can be coded like:

#include <omp.h> int my_fct() { while(1) { int result = 1; return result; } } int main() { #pragma omp sections { #pragma omp section { my_fct(); } #pragma omp section { //some other code in parallel to my_fct } } }

This is one option, take a look at OpenMP tutorials and you may find some other solutions as well.

As suggested in a comment you need to include appropriate compiler flag in order to compile with OpenMP support. It is /openmp for MS Visual C++ compiler and -fopenmp for GNU C++ compiler. You can find the correct flags for other compilers in their usage manuals.

Notice that OpenMP requires a special compiler flag to be activated. Most compilers will still compile OpenMP code without this flag, but all OpenMP #pragmas will be ignored. This is an easy mistake to make, so be sure your setup is correct.
@ComicSansMS Indeed one has to use appropriate compiler flags. I updated the answer with this notice.

Collectives™ on Stack Overflow

function run in the background c++

2 Answers 2

4 Comments

2 Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

4 Comments

2 Comments

Linked

Related