WinHelp

After you've created help files, use the WinHelp library routine to interact with the Microsoft Help application that is bundled with Windows. This allows you to perform a variety of functions such as opening one of your help files and directing Help to a particular topic. WinHelp is fully explained in the SDK documents.

$WINHELP provides a direct interface to WinHelp. The advantages to using $WINHELP are:

• you don't have to relink the runtime system
• you use a simplified calling sequence

WinHelp takes four parameters: the handle of the main application window, the name of the help file, an operation code and an operation-dependent parameter. $WINHELP takes similar parameters, but with the following differences:

• You do not pass the window-handle parameter. $WINHELP always supplies this parameter using the main ACUCOBOL-GT window. Thus, you pass (at most) three parameters to $WINHELP instead of the four that are passed to WinHelp.
• If the operation-dependent parameter is not needed, you may omit it. In this case, $WINHELP will pass a value of zero to WinHelp.
• All parameters are passed BY REFERENCE (the default for COBOL).

In summary, you pass either two or three parameters to $WINHELP. These are (in order):

1. the filename of the help file
2. the desired operation code
3. an operation-dependent parameter (which can be omitted)

As a convenience, the COBOL declarations for the operation codes can be found in the file winhelp.def. The operation codes found there exactly correspond to the operation codes documented for WinHelp in the SDK.