As we stated earlier, Winsock sockets were modeled on Berkeley sockets. Therefore, there are many similarities between them. However, there are also many differences we need to be aware of.
In this book, we will try to create each program so that it can run on both Windows and Unix-based operating systems. This is made much easier by defining a few C macros to help us with this.
As we mentioned earlier, the needed header files differ between implementations. We've already seen how these header file discrepancies can be easily overcome with a preprocessor statement.
In UNIX, a socket descriptor is represented by a standard file descriptor. This means you can use any of the standard UNIX file I/O functions on sockets. This isn't true on Windows, so we simply avoid these functions to maintain portability.
Additionally, in UNIX, all file descriptors (and therefore socket descriptors) are small, non-negative integers. In Windows...
