Other identifiers used in HELLOWIN.C are new data types, also defined in WINDOWS.H. The ones used in the program are:
| Data Type | Meaning |
| FAR | same as far |
| PASCAL | same as pascal |
| WORD | unsigned integer (16 bits) |
| DWORD | unsigned long integer (32 bits) |
| LONG | signed long integer (32 bits) |
| LPSTR | far (or long) pointer to a character string |
These are fairly self-explanatory. The people who originally developed Windows thought that it would someday be ported to other microprocessors. These new data types were defined to ease the porting of Windows applications to other architectures. Rather than use machine-specific data sizes (such as the size of C integer), the new data types were devised to keep programs consistent regardless of the processor on which they run.
Of course, Windows will probably never be ported to other architectures, but the Windows functions are still defined using these new data types, and Windows programmers continue to use them.
HELLOWIN also uses four data structures (which I'll discuss later in this chapter) defined in WINDOWS.H:
| Structure | Meaning |
| MSG | The message structure |
| WNDCLASS | The window class structure |
| PAINTSTRUCT | The paint structure |
| RECT | The rectangle structure |
The first two data structures are used in WinMain to define two structures named msg and wndclass. The second two are used in WndProc to define two structures named ps and rect.