std::any::has_value
From cppreference.com
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);
}