| Defined in header
<variant> | ||
|---|---|---|
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...
| v | - | variant to examine |
true if the variant currently holds the alternative T, false otherwise.
noexcept specification: noexcept#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
| 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) |
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