Question

is there anything wrong with this code in c++?

enum OpenMode{
    Read = 0x1,
    Write = 0x2,
    Append = 0x4
};

void main(){
    open_file("./something", OpenMode::Write); //!!!!!!!!!
}

void open_file(string name, OpenMode om){
    .
    .
    .
}

All i need to do is to pass an enum to function without creating an instance of it.

Ok, Have you ever noticed the way ios works? For example:

somefile.open(file_name, ios::in | ios::out)

I need a way to do something like this: “something::something”!

Answer 1

Yes, there’s something wrong. The names created by a enum go into the scope that contains the enum, they are not qualified by the enum‘s name.

In C++0x, there’s a new “enum class” syntax that nests the names within the enum.

A workaround in C++03 is to use a struct or namespace, i.e.:

namespace OpenMode
{
    enum OpenMode
    {
        Read = 0x1,
        Write = 0x2,
        Append = 0x4
    };
}

// blah blah OpenMode::Write

Unfortunately it also changes the type name to OpenMode::OpenMode.