# std::any::has_value

From cppreference.com
< cpp‎ | utility‎ | any

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

Checks whether the object contains a value.

### Parameters

(none)

### Return value

true if instance contains a value, otherwise false.

### Example

Run this code

    #include <any>
    #include <iostream>
    #include <string>

    int main()
    {
        std::boolalpha(std::cout);

        std::any a0;
        std::cout << "a0.has_value(): " << a0.has_value() << '\n';

        std::any a1 = 42;
        std::cout << "a1.has_value(): " << a1.has_value() << '\n';
        std::cout << "a1 = " << std::any_cast<int>(a1) << '\n';
        a1.reset();
        std::cout << "a1.has_value(): " << a1.has_value() << '\n';

        auto a2 = std::make_any<std::string>("Milky Way");
        std::cout << "a2.has_value(): " << a2.has_value() << '\n';
        std::cout << "a2 = \"" << std::any_cast<std::string&>(a2) << "\"\n";
        a2.reset();
        std::cout << "a2.has_value(): " << a2.has_value() << '\n';
    }

Output:

    a0.has_value(): false
    a1.has_value(): true
    a1 = 42
    a1.has_value(): false
    a2.has_value(): true
    a2 = "Milky Way"
    a2.has_value(): false

### See also

reset | destroys contained object (public member function)

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