std::bad_any_cast

 

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std::any

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any::any

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any::operator=

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any::emplace

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any::has_value

any::type

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swap(std::any)

any_cast

make_any

Helper classes

bad_any_cast

 

Defined in header <any>
class bad_any_cast : public std::bad_cast;		(since C++17)

Defines a type of object to be thrown by the value-returning forms of std::any_cast on failure.

Member functions

(constructor)	constructs a new bad_any_cast object (public member function)
operator=	replaces the bad_any_cast object (public member function)
what	returns the explanatory string (public member function)

std::bad_any_cast::bad_any_cast

bad_any_cast() noexcept;	(1)	(since C++17)
bad_any_cast( const bad_any_cast& other ) noexcept;	(2)	(since C++17)

Constructs a new bad_any_cast object with an implementation-defined null-terminated byte string which is accessible through what().

1) Default constructor.

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

Parameters

other

-

another exception object to copy

std::bad_any_cast::operator=

bad_any_cast& operator=( const bad_any_cast& other ) noexcept;		(since C++17)

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

Parameters

other

-

another exception object to assign with

Return value

*this

std::bad_any_cast::what

virtual const char* what() const noexcept;		(since C++17)

Returns the explanatory string.

Return value

Pointer to an implementation-defined 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.

The returned string is encoded with the ordinary literal encoding during constant evaluation.

(since C++26)

Notes

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

Inherited from std::bad_cast

Inherited from std::exception

Member functions

(destructor) [virtual]	destroys the exception object (virtual public member function of std::exception)
what [virtual]	returns an explanatory string (virtual public member function of std::exception)

Example

Run this code

#include <any>
#include <cassert>
#include <print>
 
int main()
{
    auto x = std::any(42);
    assert(std::any_cast<int>(x) == 42); // OK
 
    try
    {
        [[maybe_unused]] auto s = std::any_cast<std::string>(x); // throws
    }
    catch (const std::bad_any_cast& ex)
    {
        std::println("{}", ex.what());
    }
}

Possible output:

bad any_cast