why not work simple program example: #include<stduo.h> type

Answer 1

in c#, you can include namespaces by the "using" keyword and not "include" as used in c and c++.

e.g: using system;

Answer 2

Maybe you meant
#include<stdio.h>
but as I see, you ask the question about C# program language? There is not nor #include<stdio.h> , this is only a matter of C++ ..