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VFILT() Interactively build a filter
Description:
VFILT() provides a non-screen destructive user interface to allow the
user to select a list of fields, logical connectives and comparison
constants from pop-up light bar windows.
Syntax:
VFILT()
Pass:
Nothing
Return:
<expC> = Desired filter (blank if the user specified "no filter")
Notes:
Example:
c_Filter = VFILT()
IF EMPTY(c_Filter)
c_Filter = ".T."
ENDIF
DO WHILE &c_Filter
.
.
.
SKIP
ENDDO
Usage:
VFILT() is designed to provide the uninitiated user with an easy
interface to "filter" specification building. It is database
independent and limits the choices available in the light bar menus to
those that are applicable to the variable type selected. As the user
selects fields, relational operators and comparison constants, the
string VFILT() builds is also displayed on the screen.
VFILT() alone is not a powerful function, but when combined with the
macro substitution capabilities of Clipper, the two become very
powerful indeed. The string returned by VFILT() is suitable for macto
subsitution in the SET FILTER TO command as well as any FOR clause in
any Clipper command supporting that clause (such as REPORT, SORT,
COPY, LIST, DO WHILE, etc.)
See Also:
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