std::holds_alternative
From cppreference.com
| Defined in header <variant>
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| template <class T, class... Types> constexpr bool holds_alternative(const std::variant<Types...>& v) |
(since C++17) | |
Checks if the variant v holds the alternative T. The call is ill-formed if T appears more than once in Types...
Parameters
| v | - | variant to examine |
Return value
true if the variant currently holds the alternative T, false otherwise.
Exceptions
noexcept specification:
noexcept
Example
Run this code
#include <variant> #include <string> #include <iostream> int main() { std::variant<int, std::string> v = "abc"; std::cout << std::boolalpha << "variant holds int? " << std::holds_alternative<int>(v) << '\n' << "variant holds string? " << std::holds_alternative<std::string>(v) << '\n'; }
Output:
variant holds int? false variant holds string? true
See also
| returns the zero-based index of the alternative held by the variant (public member function) | |
| (C++17) |
reads the value of the variant given the index or the type (if the type is unique), throws on error (function template) |