std::any:: has_value

Checks whether the object contains a value.

Parameters

(none)

Return value

true if and only if the instance contains a value.

Example

#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