Why async output is not as expected

Question

Hi

Please find below code:
https://code.sololearn.com/cA15A23A6A3a

I thought that "Completed..." should be printed before result as it was computed in async task. Why output is not in proper order?

Answer 1

Async != parallelism

Parallelism is done via threads, and asynchrone is done via futures.

Answer 2

I thought argument launch::async is creating thread only...

Answer 3

Please refer below sample code. We can observe that thread ID is different for async.

https://code.sololearn.com/c6a166a6a57A