Concurrency

Every modern programming language supports concurrency, offering high-level APIs that allow the execution of many tasks simultaneously. C++ supports concurrency starting from C++11 and more sophisticated APIs got added further in C++14 and C++17. Though the C++ thread support library allows multithreading, it requires writing lengthy code using complex synchronizations; however, concurrency lets us execute independent tasks--even loop iterations can run concurrently without writing complex code. The bottom line is parallelization is made more easy with concurrency.  

The concurrency support library complements the C++ thread support library. The combined use of these two powerful libraries makes concurrent programming more easy in C++.

Let's write a simple Hello World program using C++ concurrency in the following file named main.cpp:

#include <iostream>
#include <future>
using namespace std;

void sayHello( ) {
  cout << endl << "Hello Concurrency support...