std::tuple_element<std::complex>

Since C++26

Header: <complex>

The partial specializations of std::tuple_element for std::complex provide compile-time access to the underlying real and imaginary number type of a complex, using tuple-like syntax. They are provided for structured binding support. The program is ill-formed if I >= 2.

# Declarations

template< std::size_t I, class T >
struct tuple_element<I, std::complex<T>>;

(since C++26)

# Notes

Feature-test macro Value Std Feature __cpp_lib_tuple_like 202311L (C++26) Add tuple protocol to std::complex

# Example

#include <complex>
#include <type_traits>
 
static_assert([z = std::complex<float>()]
{
    using T = decltype(z);
    return
#if __cpp_lib_tuple_like >= 202311L
        std::is_same_v<std::tuple_element_t<0, T>, float> &&
        std::is_same_v<std::tuple_element_t<1, T>, float> &&
#endif
        std::is_same_v<T::value_type, float>;
}());
 
int main() {}

# See also