Manual crystal report

dCrystal Reports 8.5: The Complete Reference

Chapter 27

Note: This chapter is taken from Crystal Reports 8.5: The Complete Reference. As such, it may refer to chapters and material in this book, and generally refers to Crystal Reports version 8.5, not 9.

Creating User Function Libraries with Visual Basic
The more sophisticated your reports get, the more sophisticated your use of CrystalReports formulas will become. Although the formula language's built- in functions will satisfy much of your sophisticated reporting requirements, you may eventually encounter situations in which you need extra features that aren't available in Crystal Reports 8.5. This often occurs when a large number of report designers in your company need a business-specific function, such as a way in which todetermine the number of days a problem ticket has been open, excluding weekends and company holidays. In some cases, you may be able to create these specialized formulas with a great deal of formula coding. In other cases, the capabilities of the built- in formula language just won't provide the necessary flexibility (perhaps your custom function will need to look up dates in a database ofcompany holidays). You have several approaches for solving this potential problem. If you're using the Report Designer Component (RDC) to integrate your report with a Visual Basic program (covered in Chapter 27), you can use all the power of Visual Basic to create a value and place it in a text object in the report. But, what if you want to be able to provide a company-specific calculation to anybodyusing the regular Crystal Report Designer, without having to integrate the report with a VB program? With a User Function Library (UFL), you can extend the capabilities of the Crystal Reports formula language with a Windows development language, such as Visual Basic.

User Function Library Overview
In the Crystal Reports Formula Editor, the Function Tree box divides functions into logical groups.Arithmetic functions are combined in their own group, date/time functions are located together, and so forth. But, if you look at the bottom of the Function Tree box, you'll see listed in an Additional Functions category an extra collection of 27-1

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functions that run the gamut from Year 2000 date conversions to financial functions,to a sound-alike function (Soundex).

All functions in this Additional Functions category are considered UFLs and are provided to Crystal Reports by way of external dynamic link library (.DLL) files. By creating a Windows .DLL file using a Windows development language, you can extend the power of the Crystal Reports formula language by adding your own functions to the Additional Functionscategory. Each of these DLLs can expose one or more functions to the Crystal Reports formula language. Crystal Reports installs several UFL DLLs by default. As with previous versions, when you initially install Crystal Reports 8.5, all the functions in the Additional Functions list are supplied by these .DLL files installed in the \CRYSTAL directory beneath the standard Windows installation directory(typically \WINDOWS or \WINNT). If you look in this directory, you'll recognize UFL filenames by the first few characters. All UFL filenames begin with the letters U2. In many (but not all) cases, the third character is the letter L, with the remaining characters describing the function of the UFL. All UFLs are DLLs that have a file extension of .DLL. Note: Crystal Reports 8.5 uses 32-bit UFLs only.In previous versions of 16-bit Crystal Reports, you could also have 16-bit UFLs. The filenames for these 16-bit UFLs contained the letter L instead of the character 2 in the second character position.

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Crystal Reports 8.5: The Complete Reference

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If you wish to create your own UFLs, you have several Windows language choices. The original Crystal Reports language...