IsMissing function
Summary
True if optional Variant not supplied.
Syntax
IsMissing(argname)
The required argname argument contains the name of an optional Variant procedure argument.
Example
Example
This example uses the IsMissing function to check if an optional argument has been passed to a user-defined procedure. Note that Optional arguments can now have default values and types other than Variant.
Dim ReturnValue
' The following statements call the user-defined function procedure.
ReturnValue = ReturnTwice() ' Returns Null.
ReturnValue = ReturnTwice(2) ' Returns 4.
' Function procedure definition.
Function ReturnTwice(Optional A)
If IsMissing(A) Then
' If argument is missing, return a Null.
ReturnTwice = Null
Else
' If argument is present, return twice the value.
ReturnTwice = A * 2
End If
End Function
This example uses the IsMissing function to check if an optional argument has been passed to a user-defined procedure. Note that Optional arguments can now have default values and types other than Variant.
Dim ReturnValue
' The following statements call the user-defined function procedure.
ReturnValue = ReturnTwice() ' Returns Null.
ReturnValue = ReturnTwice(2) ' Returns 4.
' Function procedure definition.
Function ReturnTwice(Optional A)
If IsMissing(A) Then
' If argument is missing, return a Null.
ReturnTwice = Null
Else
' If argument is present, return twice the value.
ReturnTwice = A * 2
End If
End Function