Re: [boost] [chrono] boost::chrono::floor() and negative durations

2013/11/21 Krzysztof Czainski <1czajnik@gmail.com>

2013/11/21 Howard Hinnant

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On Nov 20, 2013, at 12:49 PM, Vicente J. Botet Escriba < vicente.botet@wanadoo.fr> wrote:

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Le 20/11/13 13:45, Krzysztof Czainski a écrit :

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Hello,

The function boost::chrono::floor() is documented: "This function round down the given parameter." Therefore I expect the assert in the following program to pass, but it fails:

#include #include <cassert>

int main() { boost::chrono::nanoseconds const nsec( -1 ); boost::chrono::seconds const sec = boost::chrono::floorboost::chrono::seconds(nsec); assert( sec.count() == -1 ); }

Is this intended behavior? If yes, could the docs be updated to clarify this?

Hi,

no, there is a bug with negative numbers.

template To floor(const duration& d) { + if (d::zero()) + return duration_cast<To>(d)-To(1); + else return duration_cast<To>(d); }

Please, coul dyou create a ticket so that I don't forget it.

Thanks, Vicente

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#include <chrono>

using namespace std::chrono;

template To floor(const duration& d) { if (d::zero()) return duration_cast<To>(d)-To(1); else return duration_cast<To>(d); }

#include <iostream>

int main() { using namespace std::literals; std::cout << floor<seconds>(-1000ms).count() << '\n'; }

For me outputs:

-2

How about this instead:

template To floor(const std::chrono::duration& d) { To t = std::chrono::duration_cast<To>(d); if (t > d) --t; return t; }

Howard

Ticket #9419 created.

I think it's a bit more complicated. Doesn't Howard's version return -2 as well?

Oh, I get it now, clever ;) Regards, Kris