Odd Syntax

[acxdotfm]

I haven't coded C++ in around five years so is it some sort of new syntax convention when you do this in your header files, or is it a QT thing?

/// somefile.h

#include <QLibrary>

class Classname;
class SomeOtherClassname;

class YourClass {
private:
// etc
public:
//etc
};

The bold underlined part is the one that's new to me.