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Updated Examples and Recipes (markdown)

Howard Hinnant
2016-10-24 21:18:13 -04:00
parent bc447f5251
commit 0a0fc0c72f
1 changed files with 1 additions and 16 deletions
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17
Examples-and-Recipes.md

@@ -743,22 +743,7 @@ Assuming the birthdate is exactly synchronized with TAI (offset by the timezone)
auto birthday = to_tai_time(make_zoned(zone, auto birthday = to_tai_time(make_zoned(zone,
local_days{apr/24/1954} + 10h + 3min - 10s).get_sys_time()); local_days{apr/24/1954} + 10h + 3min - 10s).get_sys_time());
We have to subtract 10s manually because we want the birthday to be `1954-04-24 18:03:00 TAI` and without that 10s subtraction we have UTC modeled back to 1954 instead of modeling TAI in 1954. We have to subtract 10s manually because we want the birthday to be `1954-04-24 18:03:00 TAI` and without that 10s subtraction we have UTC modeled back to 1954 instead of modeling TAI in 1954. Then we add the 2Gs in `tai_time` and convert that result back to `sys_time`, and then to a `zoned_time`:
Another way to do this would be to "reinterpret_cast" the `sys_time` to `tai_time`. This would relieve us from having to know about the 10s constant. This is done with the following syntax:
auto birthday = tai_seconds{make_zoned(zone,
local_days{apr/24/1954} + 10h + 3min).get_sys_time().time_since_epoch()};
Either way, the result is the same. This line:
std::cout << "born : " << birthday << " TAI \n";
will output:
born : 1942-04-24 18:03:00 TAI
Then we add the 2Gs in `tai_time` and convert that result back to `sys_time`, and then to a `zoned_time`:
auto Day2Gs = make_zoned(zone, to_sys_time(birthday + 2'000'000'000s)); auto Day2Gs = make_zoned(zone, to_sys_time(birthday + 2'000'000'000s));