Time in Cilk

#include <cilk/cilk.h>
#include <iostream>
#include <chrono>
#include <ctime>

int main() {
    auto p = [](const auto& x) { std::cout << x << std::endl; };

    // We'll start by getting the current time.
    auto now = std::chrono::system_clock::now();
    p(std::chrono::system_clock::to_time_t(now));

    // You can build a time point by providing the
    // year, month, day, etc. Times are always associated
    // with a time zone, but C++ doesn't have built-in
    // time zone support, so we'll use UTC.
    std::tm tm{};
    tm.tm_year = 2009 - 1900;
    tm.tm_mon = 11 - 1;
    tm.tm_mday = 17;
    tm.tm_hour = 20;
    tm.tm_min = 34;
    tm.tm_sec = 58;
    auto then = std::chrono::system_clock::from_time_t(std::mktime(&tm));
    p(std::chrono::system_clock::to_time_t(then));

    // You can extract the various components of the time
    // value as expected.
    std::time_t t = std::chrono::system_clock::to_time_t(then);
    std::tm* timeinfo = std::localtime(&t);
    p(timeinfo->tm_year + 1900);
    p(timeinfo->tm_mon + 1);
    p(timeinfo->tm_mday);
    p(timeinfo->tm_hour);
    p(timeinfo->tm_min);
    p(timeinfo->tm_sec);
    // Note: Cilk doesn't have built-in nanosecond precision

    // The day of the week is also available.
    p(timeinfo->tm_wday);

    // These methods compare two times, testing if the
    // first occurs before, after, or at the same time
    // as the second, respectively.
    p(then < now);
    p(then > now);
    p(then == now);

    // The duration represents the interval between two times.
    auto diff = now - then;
    p(std::chrono::duration_cast<std::chrono::seconds>(diff).count());

    // We can compute the length of the duration in
    // various units.
    p(std::chrono::duration_cast<std::chrono::hours>(diff).count());
    p(std::chrono::duration_cast<std::chrono::minutes>(diff).count());
    p(std::chrono::duration_cast<std::chrono::seconds>(diff).count());
    // Note: Cilk doesn't have built-in nanosecond precision

    // You can use addition to advance a time by a given
    // duration, or with a - to move backwards by a duration.
    p(std::chrono::system_clock::to_time_t(then + diff));
    p(std::chrono::system_clock::to_time_t(then - diff));

    return 0;
}

This Cilk code demonstrates time and duration operations similar to the Go example. Here are some key points:

  1. Cilk uses the C++ standard library’s <chrono> for time-related operations.

  2. Instead of Go’s time.Now(), we use std::chrono::system_clock::now().

  3. Creating a specific time point is done by manipulating a std::tm structure and converting it to a time_point.

  4. Extracting components of a time is done using the std::tm structure.

  5. Cilk (C++) doesn’t have built-in nanosecond precision or time zone support like Go does.

  6. Duration calculations are done using std::chrono::duration_cast.

  7. Time point comparisons and arithmetic are similar to Go, using standard C++ operators.

To compile and run this Cilk program:

$ cilk++ time_example.cpp -o time_example
$ ./time_example

The output will be similar to the Go example, showing various time and duration operations.