I'm exploring the timestamp in C 20 returned from system_clock::now()
and when I print out the returned std::chrono::time_point
it prints the date and time in the format YYYY-MM-DD HH:MM:SS.xxxxxxx
.
Any idea what the xxxxxxx
value is? I assumed microseconds initially but I realised microseconds are to six decimal places whereas this value is always to seven.
I'm running this in VS 2022.
#include <iostream>
#include <chrono>
int main()
{
using namespace std::chrono;
auto timeDate = zoned_time{ current_zone(), system_clock::now() };
std::cout << timeDate << std::endl; // Output: 2022-07-29 08:55:22.8582577 BST
}
CodePudding user response:
It's the fractional part of a second.
The output you're getting comes from operator<<(zoned_time)
. This outputs the time in the format "{:L%F %T %Z}"
(see cppreference.com). The %T
part of the format is equivalent to "%H:%M:%S"
(reference) and the %S
specifies the seconds as a decimal floating-point number with a precision matching that of the precision of the input (i.e. the precision of
system_clock::now()
in your case).