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std:: bad_any_cast

From cppreference.net
C++
Utilities library
std::any
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.

Contents

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.

Notes

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

Inherited from std:: bad_cast

Inherited from std:: exception

Member functions

[virtual]
destroys the exception object
(virtual public member function of std::exception )
[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