When compiling cuda with visual studio 2017,

When compiling cuda with visual studio 2017, " <<< " always gives an error in a C++ file, why?

because the cuda syntax is not recognized by intellisense, since it is not standard c/c++ syntax

google “cuda red underline”

and if you are putting <<< in a file with an extension of .cpp, that is just a mistake. It belongs in a file with extension of .cu, in a CUDA project.

Thank you, thank you very much.
As a beginner, your answer is very helpful to me.