The WinMain function uses several special data types to define its parameters. For example, it uses the HANDLE data type to define the hinstCurrent and hinstPrevious parameters, and the LPSTR data type to define the lpszCmdLine parameter. In general, Windows applications use many more data types than are found in a typical C-language application. Although the Windows data types are often equivalent to familiar C-language data types, they are intended to be more descriptive and should help you better understand the purpose of a variable or parameter used in an application.
The Windows data types are defined in the WINDOWS.H header file. This file is an ordinary C-language source file that contains definitions for all the Windows special constants, variables, structures, and functions. To use these definitions, you must include the WINDOWS.H file in each source file. Place the following line at the beginning of your source file:
#include <windows.h> /* required for all Windows applications */Following are some commonly used Windows data types:
| Type | Meaning |
| WORD | Specifies a 16-bit, unsigned integer. |
| LONG | Specifies a 32-bit, signed integer. |
| HANDLE | Identifies a 16-bit, unsigned integer to be used as a handle. |
| HWND | Identifies a 16-bit, unsigned integer to be used as a handle of a window. |
| LPSTR | Specifies a 32-bit address of a character string (of type char) |
| FARPROC | Specifies a 32-bit address of a function. |
Following are some commonly used structures:
| Structure | Description |
| MSG | Contains information about an input message from the Windows application queue. |
| WNDCLASS | Defines a window class. |
| PAINTSTRUCT | Defines a structure used to paint the client area of a window. |
| RECT | Defines a rectangle. |
For a complete listing and description of Windows data types and structures, see the Microsoft Windows Programmer's Reference, Volume 3.