std::get (std::variant)
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                    | Defined in header  <variant> | ||
| (1) | (since C++17) | |
| template <std::size_t I, class... Types> constexpr std::variant_alternative_t< | ||
| template <std::size_t I, class... Types> constexpr std::variant_alternative_t< | ||
| template <std::size_t I, class... Types> constexpr std::variant_alternative_t< | ||
| template <std::size_t I, class... Types> constexpr std::variant_alternative_t< | ||
| (2) | (since C++17) | |
| template <class T, class... Types> constexpr T& get(std::variant<Types...>& v); | ||
| template <class T, class... Types> constexpr T&& get(std::variant<Types...>&& v); | ||
| template <class T, class... Types> constexpr const T& get(const std::variant<Types...>& v); | ||
| template <class T, class... Types> constexpr const T&& get(const std::variant<Types...>&& v); | ||
1) Index-based value accessor: If v.index() == I, returns a reference to the value stored in 
v. Otherwise, throws std::bad_variant_access. The call is ill-formed if I is not a valid index in the variant.2) Type-based value accessor: If v holds the alternative 
T, returns a reference to the value stored in v. Otherwise, throws std::bad_variant_access. The call is ill-formed if T is not a unique element of Types....| Contents | 
[edit] Parameters
| I | - | index to look up | 
| Type | - | unique type to look up | 
| v | - | a variant | 
[edit] Return value
Reference to the value stored in the variant.
[edit] Exceptions
1,2) Throws std::bad_variant_access on errors.
[edit] Example
Run this code
#include <variant> #include <string> int main() { std::variant<int, float> v{12}, w; int i = std::get<int>(v); w = std::get<int>(v); w = std::get<0>(v); // same effect as the previous line // std::get<double>(v); // error: no double in [int, float] // std::get<3>(v); // error: valid index values are 0 and 1 try { std::get<float>(w); // w contains int, not float: will throw } catch (std::bad_variant_access&) {} }
 
[edit] See also
| (C++17) | obtains a pointer to the value of a pointed-to variant given the index or the type (if unique), returns null on error (function template) | 
| tuple accesses specified element (function template) | |
| accesses an element of an array(function template) | |
| (C++11) | accesses an element of a pair(function template) | 


