HowardHinnant/date
1
0
Fork 1
mirror of https://github.com/HowardHinnant/date.git synced 2025-08-05 21:54:27 +02:00
Code Issues Packages Projects Releases Wiki Activity

Updated Examples and Recipes (markdown)

HowardHinnant
2015-08-01 20:45:38 -04:00
parent 780ae4508f
commit 654ee4fa83
1 changed files with 28 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

28
Examples-and-Recipes.md

@@ -3,6 +3,7 @@ This page contains examples and recipes contributed by community members. Feel f
##Contents
- [Obtaining a `time_point` from `y/m/d h:m:s` components](#time_point_to_components)
- [Obtaining `y/m/d h:m:s` components from a `time_point`](#components_to_time_point)
- [Normalizing `y/m/d` when it is `!ok()`](#normalize)
***
@@ -99,6 +100,33 @@ std::cout << t.tm_year << "-" << t.tm_mon << "-" << t.tm_day << " ";
<< t.tm_hour << ":" << t.tm_min << ":" << t.tm_sec << "\n";
```
<a name="normalize"></a>
### Normalizing `y/m/d` when it is `!ok()`
(by [Howard Hinnant](https://github.com/HowardHinnant))
The following function will "normalize" a `year_month_day`, much like `mktime` normalizes a `tm`. This function is not part of the library, but is offered as an example if you find your self needing things like this:
date::year_month_day
normalize(date::year_month_day ymd)
{
using namespace date;
ymd += months{0};
ymd = day_point(ymd);
return ymd;
}
The first line simply adds 0 months to the `ymd`. If `ymd.month()` is 0, with will subtract one from the `year` and set the month to `Dec`. If `ymd.month()` is greater than 12, the year will be incremented as many times as appropriate, and the month will be brought within the proper range. This operation will do nothing if `ymd.month().ok()` is already true.
The second line will "normalize" the day field. The second line requires that the month field is already normalized. For example `2015_y/dec/32` will become `2016_y/jan/1`. If the day field is already in range, there will be no change.
The conversion from `year_month_day` to `day_point` calls this algorithm:
http://howardhinnant.github.io/date_algorithms.html#days_from_civil
And the conversion from `day_point` back to `year_month_day` calls this algorithm:
http://howardhinnant.github.io/date_algorithms.html#civil_from_days
***
![CC BY Logo](http://mirrors.creativecommons.org/presskit/buttons/80x15/svg/by.svg) _This work is licensed under a [Creative Commons Attribution 4.0 International License](http://creativecommons.org/licenses/by/4.0/)._