Unix Timestamp in C++

Look up the current epoch time and convert between Unix seconds and UTC dates in C++.

Get the current timestamp

#include <chrono>
#include <iostream>

int main() {
    using namespace std::chrono;
    std::cout << floor<seconds>(system_clock::now()).time_since_epoch().count() << '\n';
}

Timestamp to date

#include <ctime>
#include <iomanip>
#include <iostream>

int main() {
    std::time_t value = 1'700'000'000;
    std::cout << std::put_time(std::gmtime(&value), "%Y-%m-%dT%H:%M:%SZ") << '\n';
}

Date to timestamp

#include <chrono>
#include <iostream>

int main() {
    using namespace std::chrono;
    auto utc = sys_days{year{2023}/November/14} + hours{22} + minutes{13} + seconds{20};
    std::cout << utc.time_since_epoch().count() << '\n';
}

Open 1700000000 in the converter

Current Unix time

Seconds—

Milliseconds—

UTC: —
My time zone: —

Official reference ↗

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How to use it

Copy the current-time example into your C++ environment to read Unix seconds.
Run the second example to display 1700000000 as a UTC date.
Run the last example to convert that date back into seconds.

These examples use the C++20 calendar API. sys_seconds represents whole seconds on the system-clock timeline, and sys_days constructs a UTC calendar day.