Keyword Searches

You can enable the user to find and view topics by assigning keywords to topics in the help file. A keyword is simply a string that is associated with one or more topics. Windows Help collects all keywords in a help file, places them in a table, and displays them in the Index list of the Help Topics dialog box. When the user selects a keyword, Windows Help displays the associated help topic or displays a list of topics from which the user can choose if there is more than one topic associated with the keyword.

In an application, you can use the HELP_KEY, HELP_PARTIALKEY, or HELP_MULTIKEY command with WinHelp to search for and display help topics based on whole or partial keywords. You specify the command, the keyword string, the help file, and the handle of the owner window. In all cases, if a single match is found, WinHelp displays the corresponding topic. If more than one match is found, the function displays the Topics Found dialog, letting the user choose which topic to view. If no match is found, WinHelp either displays the Index list (for HELP_KEY and HELP_PARTIALKEY) or displays an error message (for HELP_MULTIKEY).

You can search for multiple keywords in a single call to WinHelp by separating each keyword from the preceeding one with a semicolon (;). (Searching for multiple keywords is not supported for help files created for version 3.x.) You can also search for a keywords across multiple help files if the help file that you specify has a contents (.CNT) file that contains :Index or :Link commands. With the HELP_KEY command, WinHelp searches for keywords in all files specified by these commands. With the HELP_MULTIKEY and HELP_PARTIALKEY commands, the function searches all files except those specified by :Link commands.

By default, Windows Help recognizes only the keyword table identified by the K footnote character in the help source file. You can direct Windows Help to create additional keyword tables by specifying a footnote character other than K with the keyword definitions in the Windows Help file. (The footnote character A, however, is reserved.) You must define any additional keyword tables by using MULTIKEY statements in the [OPTIONS] section of the project file when building the help file.

An application can use the HELP_SETINDEX command with the WinHelp function to direct Windows Help to display a keyword table other than K in its Index list. To direct Windows Help to search for a keyword in an alternate keyword table, an application can use the HELP_MULTIKEY command. You specify the keyword and keyword table in a MULTIKEYHELP structure, which you pass to WinHelp.

When WinHelp displays a topic, it displays it in the window specified by the > footnote for the topic, or in the window specified by the :Base command in the contents file, or in the main window. If the main window is already open to a different help file when you call WinHelp, the function hides main window while searching. In this case, canceling both the Topics Found and Help Topics dialogs, close the main window.

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