Can I include a headerfile in a namespace?

Question

I am using the <conio.h> header file, and somewhere else in my source code I define a function with the name getch and it has to have that name. Since there already is a getch in <conio.h>, and this header file declares all of its functions in the global namespace, I get a name collision.

I found that using the following syntax would avoid the collision:

namespace some_namespace
{
    #include <conio.h>
}

Then I can use some_namespace::getch when I want to access the function in <conio.h> and getch when I want to access my own function.

Is this valid syntax? I know <conio.h> is only for windows, but is this kind of syntax going to behave the same across all the compilers? What other ways do you suggest to get around this problem?

Edit:

I use GCC and MSVC 2019 on Windows and it compiles fine on both of them.

I can access the functions in <conio.h> as well, getch in particular as I showed above (even though I should use the name _getch instead of getch in MSVC).

Answer 1

System header files like <conio.h> which are intended to be used in both C and C++ will enclose their declarations in an extern C scope, forcing C linkage for all that is contained in them, regardless of whatever additional C++ namespaces you add. That’s why your code compiles in this case.

See also this, which is almost a duplicate of this question, but not exactly.

In short, yes it’s valid, but I would strongly encourage against it. There are many other ways to solve this problem, like creating wrapper modules for the functions you want to have alternate symbols for.

As a side note: try putting your own getch in an extern C block. My guess is you’ll get a linker error.