ambiguous_local_time.mdx

title	std::chrono::ambiguous_local_time
cppdoc	keys revision cpp.chrono.ambiguous_local_time since C++20

import { CppHeader } from "@components/header"; import { Decl, DeclDoc } from "@components/decl-doc"; import { Desc, DescList } from "@components/desc-list"; import { ParamDoc, ParamDocList } from "@components/param-doc"; import Missing from "@components/Missing.astro"; import { Revision, RevisionBlock } from "@components/revision";

Defined in header .

```cpp class ambiguous_local_time; ```

Defines a type of object to be thrown as exception to report that an attempt was made to convert an ambiguous std::chrono::local_time to a std::chrono::sys_time without specifying a std::chrono::choose (such as choose::earliest or choose::latest).

This exception is thrown by std::chrono::time_zone::to_sys and functions that call it (such as the constructors of std::chrono::zoned_time that take a std::chrono::local_time).

Member functions

`(constructor)` constructs the exception object `operator=` replaces the exception object `what` returns the explanatory string

std::chrono::ambiguous_local_time::ambiguous_local_time

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

The explanatory string returned by what() is equivalent to that produced by os.str() after the following code:

std::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";

The behavior is undefined if i.result != std::chrono::local_info::ambiguous.

```cpp ambiguous_local_time( const ambiguous_local_time& other ) noexcept; ```

Copy constructor. If *this and other both have dynamic type std::chrono::ambiguous_local_time then std::strcmp(what(), other.what()) == 0.

Parameters

the time point for which conversion was attempted a `std::chrono::local_info` describing the result of the conversion attempt another `ambiguous_local_time` to copy

Exceptions

May throw std::bad_alloc.

Notes

Because copying a standard library class derived from std::exception is not permitted to throw exceptions, this message is typically stored internally as a separately-allocated reference-counted string.

std::chrono::ambiguous_local_time::operator=

```cpp ambiguous_local_time& operator=( const ambiguous_local_time& other ) noexcept; ```

Assigns the contents with those of other. If *this and other both have dynamic type std::chrono::ambiguous_local_time then std::strcmp(what(), other.what()) == 0 after assignment.

Parameters

another exception object to assign with

Return value

*this

std::chrono::ambiguous_local_time::what

```cpp virtual const char* what() const noexcept; ```

Returns the explanatory string.

Parameters

(none)

Return value

Pointer to a null-terminated string with explanatory information. The string is suitable for conversion and display as a std::wstring. The pointer is guaranteed to be valid at least until the exception object from which it is obtained is destroyed, or until a non-const member function (e.g. copy assignment operator) on the exception object is called.

Notes

Implementations are allowed but not required to override what().

Inherited from std::runtime_error

Inherited from std::exception.

Member functions

`what` returns an explanatory string

See also

`nonexistent_local_time` exception thrown to report that a local time is nonexistent