When writing header files I've always used the folowing format
Now I've bought a C++ .Net book and it uses an alternative approach:
Is this better or worse or does it not make any difference which one I use?
is NOT defined in C++ and therefore is not guaranteed to be portable from compiler to compiler. It's in the .NET book because they are most-likely assuming you are using MSVC++ .NET (a compiler which defines the command to only open the file it is in once).