Unix timestamp with microsecond precision

timestamp.cpp

#include <chrono>   // std::chrono::high_resolution_clock, std::chrono::duration
#include <iostream> // std::cout
#include <iomanip>  // std::fixed

int main() {
  auto now = std::chrono::high_resolution_clock::now();
  auto timestamp = std::chrono::duration<double>(now.time_since_epoch()).count();
  std::cout << std::fixed << timestamp << std::endl;
}

This code uses the chrono library, which is part of C++11. You may need to add the compile flag -std=c++11 (or equivalent).

As an explanation, I made this to be able to track time in shell scripts with more precision than date +%s