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
vholds 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....
[edit] Template parameters I - index to look up T - unique type to look up Types... - types forming thevariant [edit] Parameters [edit] Return value
Reference to the value stored in the variant.
[edit] Exceptions [edit] Example#include <iostream>
#include <string>
#include <variant>
int main()
{
std::variant<int, float> v{12}, w;
std::cout << std::get<int>(v) << '\n';
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
{
w = 42.0f;
std::cout << std::get<float>(w) << '\n'; // ok, prints 42
w = 42;
std::cout << std::get<float>(w) << '\n'; // throws
}
catch (std::bad_variant_access const& ex)
{
std::cout << ex.what() << ": w contained int, not float\n";
}
}
Possible output:
12 42 Unexpected index: w contained int, not float[edit] See also
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