[time.zone.exception.ambig]

# 30 Time library [[time]](./#time)

## 30.11 Time zones [[time.zone]](time.zone#exception.ambig)

### 30.11.3 Exception classes [[time.zone.exception]](time.zone.exception#ambig)

#### 30.11.3.2 Class ambiguous_local_time [time.zone.exception.ambig]

namespace std::chrono {class ambiguous_local_time : public runtime_error {public:template<class Duration> ambiguous_local_time(const local_time<Duration>& tp, const local_info& i); };}

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/time.tex#L9169)

ambiguous_local_time is thrown when
an attempt is made
to convert an ambiguous local_time to a sys_time without specifying choose​::​earliest or choose​::​latest[.](#1.sentence-1)

[ð](#lib:ambiguous_local_time,constructor)

`template<class Duration>
  ambiguous_local_time(const local_time<Duration>& tp, const local_info& i);
`

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/time.tex#L9182)

*Preconditions*: i.result == local_info​::​ambiguous is true[.](#2.sentence-1)

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/time.tex#L9186)

*Effects*: Initializes the base class with a sequence of char equivalent to that produced by os.str() initialized as shown below:ostringstream os;
os << tp << " is ambiguous. It could be\n"<< tp << ' ' << i.first.abbrev << " == "<< tp - i.first.offset << " UTC or\n"<< tp << ' ' << i.second.abbrev << " == "<< tp - i.second.offset << " UTC";

[4](#4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/time.tex#L9200)

[*Example [1](#example-1)*: #include <chrono>#include <iostream>int main() {using namespace std::chrono; try {auto zt = zoned_time{"America/New_York",
 local_days{Sunday[1]/November/2016} + 1h + 30min}; } catch (const ambiguous_local_time& e) { std::cout << e.what() << '\n'; }}

Produces the output:

```
2016-11-06 01:30:00 is ambiguous.  It could be
2016-11-06 01:30:00 EDT == 2016-11-06 05:30:00 UTC or
2016-11-06 01:30:00 EST == 2016-11-06 06:30:00 UTC

```

â *end example*]
