async_example1.cpp

#include <string>
#include <chrono>
#include <thread>
#include <iostream>

using namespace std::chrono;

auto calculation1(std::string d) {
  std::this_thread::sleep_for(seconds(5));
  return "cal1_" + d;
}

auto calculation2(std::string d) {
  std::this_thread::sleep_for(seconds(5));
  return "cal2_" + d;
}

int main() {
  auto start = system_clock::now();

  auto data1 = calculation1("Data");
  auto data2 = calculation2("Data");

  auto end = system_clock::now();
	
  auto diff = duration_cast<seconds>(end - start).count();
  std::cout << "Total Time = " << diff << " Seconds" << std::endl;
	
  //Combine The Data
  auto data = data1 + "::" + data2;

  //Printing the combined Data
  std::cout << "Data = " << data << std::endl;
  return 0;
}

async_example2.cpp

#include <string>
#include <chrono>
#include <thread>
#include <iostream>
#include <future>

using namespace std::chrono;

auto calculation1(std::string d) {
  std::this_thread::sleep_for(seconds(5));
  return "cal1_" + d;
}

auto calculation2(std::string d) {
  std::this_thread::sleep_for(seconds(5));
  return "cal2_" + d;
}

int main() {
  auto start = system_clock::now();

  //auto data1 = calculation1("Data");  
  auto futureData1 = std::async(std::launch::async, calculation1, "Data");
  auto data2 = calculation2("Data");
  // auto resultData2 = std::async(std::launch::async, calculation2, "Data");

  auto end = system_clock::now();
	
  auto diff = duration_cast<seconds>(end - start).count();
  std::cout << "Total Time = " << diff << " Seconds" << std::endl;
	
  //Combine The Data
  //auto data = data1 + "::" + data2;
  auto data = futureData1.get() + "::" + data2;

  //Printing the combined Data
  std::cout << "Data = " << data << std::endl;
  return 0;
}