std::isnan C++ Numerics library Common mathematical functions Defined in header<cmath> (1) boolisnan(floatnum); boolisnan(doublenum); boolisnan(longdoublenum); (since C++11) (until C++23) constexprboolisnan(/*floating-point-type*/num); ...
std::move和std::forward只是执行转换的函数(确切的说应该是函数模板)。std::move无条件的将它的参数...