C++11: Time

Three time systems were added. Here is an example:

#include <chrono>
#include <ctime>
#include <iostream>

int main()
{
////
  std::chrono::system_clock::time_point syc_now      = 
                                         std::chrono::system_clock::now();
  std::chrono::system_clock::time_point syc_default  ;
  std::chrono::system_clock::duration   syc_duration = syc_now -
                                                              syc_default;

  double syc_seconds = double(syc_duration.count())           *
                       std::chrono::system_clock::period::num /
                       std::chrono::system_clock::period::den; 

  std::cout << syc_seconds << std::endl;
////
  std::chrono::steady_clock::time_point stc_now     =                                             std::chrono::steady_clock::now();
  std::chrono::steady_clock::time_point stc_default ;
  std::chrono::steady_clock::duration   stc_duration = stc_now -
                                                            stc_default;

  double std_seconds = double(stc_duration.count())           *
                       std::chrono::steady_clock::period::num /
                       std::chrono::steady_clock::period::den;  

  std::cout << std_seconds << std::endl;
////
  std::chrono::high_resolution_clock::time_point hrc_now      =                                   std::chrono::high_resolution_clock::now();
  std::chrono::high_resolution_clock::time_point hrc_default  ;
  std::chrono::high_resolution_clock::duration   hrc_duration = 
                                                   hrc_now - hrc_default;

  double hrc_seconds = double(hrc_duration.count())                    *
                       std::chrono::high_resolution_clock::period::num /
                       std::chrono::high_resolution_clock::period::den;  

  std::cout << hrc_seconds << std::endl;
////
  std::time_t tt_now = std::time(nullptr);

  std::cout << tt_now << std::endl;
  return 0;
}
/* Output:
     1.50396e+09
     33785.6
     33785.6
     1503960804
*/

Reference: http://www.cplusplus.com/reference/chrono/