std::holds_alternative
Defined in header <variant> | ||
|---|---|---|
template< class T, class... Types > constexpr bool holds_alternative( const std::variant<Types...>& v ) noexcept; | (since C++17) |
Checks if the variant v holds the alternative T. The call is ill-formed if T does not appear exactly once in Types...
Parameters
| v | - | variant to examine |
Return value
true if the variant currently holds the alternative T, false otherwise.
Example
#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));
}
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) |
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