IIf oddity

[GTBecker]

With compiler v4.2.3 I find this odd behavior of IIf, extracted from Steve's DS1307functions code:

Code: Select all

private strMonths as StringVectorData({
   "Jan", "Feb", "Mar", "Apr", "May", "Jun", 
   "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" })

public Function MonthName(byval n as byte) as String
    MonthName = iif&#40;&#40;n>0 and n<13&#41;, strMonths&#40;n&#41;, "?"&#41;
end function

sub main&#40;&#41;
    dim i as byte
    for i= 0 to 14
        debug.print &#40;n>0 and n<13&#41;; " ";
        debug.print MonthName&#40;i&#41;
    next
end sub

which yields:
?
Jan
?
Mar
?
May
?
Jul
?
Sep
?
Nov
?
?

If the (n>0 and n<13) test is executed outside of IIf, however, the behavior is correct:

Code: Select all

private strMonths as StringVectorData({
   "Jan", "Feb", "Mar", "Apr", "May", "Jun", 
   "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" })

public Function MonthName(byval n as byte) as String
    dim tf as boolean
    tf = &#40;n>0 and n<13&#41;
    MonthName = iif&#40;tf, strMonths&#40;n&#41;, "?"&#41;
end function

sub main&#40;&#41;
    dim i as byte
    for i= 0 to 14
        debug.print MonthName&#40;i&#41;
    next
end sub

yielding:
?
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
?
?

as expected.

[dkinzer]

With compiler v4.2.3 I find this odd behavior of IIf [...]

The issue has been confirmed and a correction is being developed. In the interim, one can get the correct behavior by introducing an intermediate variable thus:

Code: Select all

Public Function MonthName(ByVal n as Byte) as String
    Dim idxOK as Boolean = &#40;&#40;n>0&#41; and &#40;n<13&#41;&#41;
    MonthName = IIF&#40;idxOK, strMonths&#40;n&#41;, "?"&#41;
End Function

Another alternative is:

Code: Select all

Public Function MonthName(ByVal n as Byte) as String
    MonthName = IIF&#40;Not&#40;n<1&#41; and &#40;n<13&#41;, strMonths&#40;n&#41;, "?"&#41;
End Function