What would be a “Hello, World!” example for “std::ref”?

Question

Can somebody give a simple example which demonstrates the functionality of std::ref? I mean an example in which some other constructs (like tuples, or data type tem

Answer 1

Another place where you may need std::ref is when passing objects to threads where you want each thread to operate on the single object and not a copy of the object.

int main(){
BoundedBuffer buffer(200);

std::thread c1(consumer, 0, std::ref(buffer));
std::thread c2(consumer, 1, std::ref(buffer));
std::thread c3(consumer, 2, std::ref(buffer));
std::thread p1(producer, 0, std::ref(buffer));
std::thread p2(producer, 1, std::ref(buffer));

c1.join();
c2.join();
c3.join();
p1.join();
p2.join();

return 0; }

where you wish various functions running in various threads to share a single buffer object. This example was stolen from this excellent tutorial ( C++11 Concurrency Tutorial - Part 3: Advanced locking and condition variables (Baptiste Wicht) ) (hope I did the attribution correctly)