Excel Add-in Development in C/C++: Applications in ... - F9

34 Excel Add-in Development in C/C++2.14.1 Function categoryIn the left-hand list box are all the function categories, the top two being special categorieswith obvious meanings. All functions are otherwise listed under one and only one specificcategory. Many of these categories are hard-coded Excel standards. Add-ins can addfunctions to existing categories or can create their own, or do both. If functions havebeen defined in a VB module or have been loaded by the Add-in Manager from an XLAadd-in file, then the category UDF (in Excel 2000) or User Defined (in Excel 2002 andlater) appears and the functions are listed under that.2.14.2 Function name, argument list and descriptionSelecting a category will cause all the functions in that category to be listed in alphabeticalorder in the right-hand list box. The figure shows the Logical category selected and allsix logical functions. Selecting a function name causes the name as it appears in thespreadsheet, a named comma-separated argument list and a description of the functionto be displayed below the list boxes. In the above example the arguments and functiondescription for the IF() function are shown.2.14.3 Argument construction dialogPressing OK in the Paste Function dialog causes the argument construction dialog toappear for the highlighted function. Invoking the Paste Function command on an activecell containing a function has the same effect. The figure below shows this for the IF()function. Where invoked on an empty cell the dialog is blank. Where invoked on anexisting formula, the fields are populated with the expressions read from the cell’s formula.This dialog has a number of important features that should be understood by anyonewanting to enable users to access their own add-in functions in this way. These arehighlighted in the following diagram which shows the Excel 2000 dialog.12345Figure 2.5 Paste Function argument construction dialog (Excel 2000)(1) Argument name – from the argument list in the Paste Function dialog. (Bold typeindicates a required argument; normal type, an optional one.)(2) Argument expression text box – into which the user enters the expression that Excelevaluates in preparation for the function call.