std::any::has_value

 

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std::any

Member functions

any::any

any::~any

any::operator=

Modifiers

any::emplace

any::reset

any::swap

Observers

any::has_value

any::type

Non-member functions

swap(std::any)

any_cast

make_any

Helper classes

bad_any_cast

 

bool has_value() const noexcept;		(since C++17)

Checks whether the object contains a value.

Parameters

(none)

Return value

true if and only if the instance contains a value.

Example

Run this code

#include <any>
#include <cassert>
#include <string>
 
int main()
{
    std::any a0;
    assert(a0.has_value() == false);
 
    std::any a1 = 42;
    assert(a1.has_value() == true);
    assert(std::any_cast<int>(a1) == 42);
    a1.reset();
    assert(a1.has_value() == false);
 
    auto a2 = std::make_any<std::string>("Andromeda");
    assert(a2.has_value() == true);
    assert(std::any_cast<std::string&>(a2) == "Andromeda");
    a2.reset();
    assert(a2.has_value() == false);
}

See also

reset

destroys contained object (public member function)