What is the difference between C++ and Java timestamps?

Question

In a project using JSON as an exchange, we encountered the problem that timestamps in milliseconds in C++ and Java are completely different even though both are described as a long primitive data type.

What kind of standards does each language use and why is there a difference?

As an example, 1407315600 is a C++ timestamp which refers to 06.08.2014 09:00:00 UTC while in Java it's unreadable!

Reading timestamps in Java is done using new Date(1407315600).

It depends how do you use this long in Java. Usually timestamps are in milliseconds. Add your Java code if you want more help... — BobTheBuilder, Oct 13 '14 at 12:48
Can you please show us how you read this timestamp with Java? — Supamiu, Oct 13 '14 at 12:48
Reading the date timestamp is usually done using `new Date(long)`. Please check my updated answer. — Mohamed Taher Alrefaie, Oct 13 '14 at 12:55
Try `new Date(1407315600 * 1000)`. The java date requires milliseconds, the C++ timestamp you have looks like it is in seconds. — Niall, Oct 13 '14 at 13:10
In c++ time in **seconds** since 1970, in java time in **milliseconds** since 1970 — user1516873, Oct 13 '14 at 13:12

score 2 · Accepted Answer · edited May 23 '17 at 10:28

Try

new Date(1407315600 * 1000)

The Java date requires milliseconds, the C++ timestamp you have looks like it is in seconds.

In general, the C++ time_t functions give the time in seconds since the epoch.

To get the time in milliseconds in C++ (compared to Java), please refer to this.

C++11

If C++11 is available on the platform, the chrono::high_resolution_clock could be used to obtain a higher resolution (note; the clock may be an alias for one of the other clocks or an implementation defined clock).

#include <iostream>
#include <chrono>

int main()
{
    using namespace std;
    using namespace std::chrono;

    milliseconds ms;
    ms = duration_cast<milliseconds>(high_resolution_clock::now().time_since_epoch());
    cout << ms.count() << endl;
}

What is the difference between C++ and Java timestamps?

1 Answers1