std::holds_alternative
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std::variant
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holds_alternative
Defined in header
<variant>
template< class T, class... Types >
constexpr bool holds_alternative( const std::variant <Types...>& v ) noexcept;
(since C++17)
constexpr bool holds_alternative( const std::variant <Types...>& v ) noexcept;
Checks if the variant v holds the alternative T. The call is ill-formed if T does not appear exactly once in Types...
Contents
[edit] Parameters
v
-
variant to examine
[edit] Return value
true if the variant currently holds the alternative T, false otherwise.
[edit] Example
Run this code
#include <cassert> #include <string> #include <variant> int main() { std::variant <int, std::string > v = "abc"; assert (not std::holds_alternative<int>(v)); assert (std::holds_alternative<std::string >(v)); }
[edit] See also
(C++17)
(function template) [edit]