HowardHinnant/date
1
0
Fork 1
mirror of https://github.com/HowardHinnant/date.git synced 2025-08-05 05:34:27 +02:00
Code Issues Packages Projects Releases Wiki Activity

Updated Examples and Recipes (markdown)

Howard Hinnant
2019-03-30 20:26:19 -04:00
parent 7396a889c5
commit b8f0698a33
1 changed files with 12 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
Examples-and-Recipes.md

@@ -261,7 +261,7 @@ to_tm(date::zoned_seconds tp)
t.tm_mon = (ymd.month() - January).count();
t.tm_year = (ymd.year() - 1900_y).count();
t.tm_wday = (weekday{ld} - Sunday).count();
t.tm_yday = (ld - local_days{ymd.year()/jan/1}).count();
t.tm_yday = (ld - local_days{ymd.year()/January/1}).count();
t.tm_isdst = tp.get_info().save != minutes{0};
return t;
}
@@ -330,7 +330,7 @@ to_nanoseconds(timespec const& ts)
One just converts the integrals to their proper `duration` types and adds them. The result has type `nanoseconds`.
We can resume the above the above function to convert to a `time_point`:
We can reuse the above the above function to convert to a `time_point`:
```c++
date::sys_time<std::chrono::nanoseconds>
@@ -412,7 +412,7 @@ since_local_midnight(std::chrono::system_clock::time_point t, const date::time_z
{
using namespace date;
using namespace std::chrono;
auto zt = make_zoned(zone, t);
zoned_time zt{zone, t};
zt = floor<days>(zt.get_local_time());
return floor<milliseconds>(t - zt.get_sys_time());
}
@@ -440,14 +440,14 @@ since_local_midnight(const date::zoned_seconds& zt)
So to output the current time in milliseconds since the local midnight, you would just:
```c++
std::cout << since_local_midnight().count() << "ms\n";
std::cout << since_local_midnight() << '\n';
```
To ensure that our function is working, it is worthwhile to output a few example dates. This is most easily done by specifying a time zone (I'll use "America/New_York"), and some local date/times where I know the right answer:
```c++
auto zt = make_zoned(locate_zone("America/New_York"), local_days{jan/15/2016} + 3h);
std::cout << zt << " is " << since_local_midnight(zt).count() << "ms after midnight\n";
zoned_time zt{locate_zone("America/New_York"), local_days{January/15/2016} + 3h};
std::cout << zt << " is " << since_local_midnight(zt) << " after midnight\n";
```
This 3am in the middle of the Winter. This outputs:
@@ -459,8 +459,8 @@ which is correct (10800000ms == 3h).
I can run the test again just by assigning a new local time to `zt`. The following is 3am just after the "spring forward" daylight saving transition (2nd Sunday in March):
```c++
zt = local_days{sun[2]/mar/2016} + 3h;
std::cout << zt << " is " << since_local_midnight(zt).count() << "ms after midnight\n";
zt = local_days{Sunday[2]/March/2016} + 3h;
std::cout << zt << " is " << since_local_midnight(zt) << " after midnight\n";
```
This outputs:
@@ -472,16 +472,16 @@ Because the local time from 2am to 3am was skipped, this correctly outputs 2 hou
An example from the middle of Summer gets us back to 3 hours after midnight:
```c++
zt = local_days{jul/15/2016} + 3h;
std::cout << zt << " is " << since_local_midnight(zt).count() << "ms after midnight\n";
zt = local_days{July/15/2016} + 3h;
std::cout << zt << " is " << since_local_midnight(zt) << " after midnight\n";
```
2016-07-15 03:00:00 EDT is 10800000ms after midnight
And finally an example just after the Fall transition from daylight saving back to standard gives us 4 hours:
```c++
zt = local_days{sun[1]/nov/2016} + 3h;
std::cout << zt << " is " << since_local_midnight(zt).count() << "ms after midnight\n";
zt = local_days{Sunday[1]/November/2016} + 3h;
std::cout << zt << " is " << since_local_midnight(zt) << " after midnight\n";
```
2016-11-06 03:00:00 EST is 14400000ms after midnight