std::variant_npos (3) - Linux Manuals
std::variant_npos: std::variant_npos
NAME
std::variant_npos - std::variant_npos
Synopsis
Defined in header <variant>
inline constexpr std::size_t variant_npos = -1; (since C++17)
This is a special value equal to the largest value representable by the type std::size_t, used as the return type of index() when valueless_by_exception() is true
See also
index (public member function)
valueless_by_exception (public member function)