Optional arguments in function

[MetLife]

Hi,

I have a function with optional inputs. The thing is I need some way of knowing was an input entered or not. How do I do this?

Function Read(i1 As Integer, Optional i2 As Integer, Optional i3 As Integer, Optional i4 As Integer)

How do I tell if "i4" was entered or not?

Thanks

 

[sheetspread]

If you have Excel 2013 or later maybe the formulatext function, otherwise more VBA.

 

[Hendy2322]

There are two ways I can think of:

Option 1:
You can declare optional parameters of any data type and provide a default value to be used if that parameter is omitted.

'Option 1
Function Read(i1 As Integer, Optional i2 As Integer = 9999, Optional i3 As Variant = 9999, Optional i4 As Variant = 9999)
    
    If i2 = 9999 Then
        MsgBox "Parameter i2 not passed"
    End If
    
    If i3 = 9999 Then
        MsgBox "Parameter i3 not passed"
    End If
    
    If i4 = 9999 Then
        MsgBox "parameter i4 not passed"
    End If
    
End Function

Option 2:
If you change the datatype of the Optional variables to Variant then you can use the IsMissing function to determine if the parameter was passed. It will return false for any other datatype, even if that parameter is declared as optional and is in fact missing. It also won't work if you assign a default value to the Optional Variant variable.

'Option 2
Function Read(i1 As Integer, Optional i2 As Variant, Optional i3 As Variant, Optional i4 As Variant)
    
    If IsMissing(i2) Then
        MsgBox "Parameter i2 not passed"
    End If
    
    If IsMissing(i3) Then
        MsgBox "Parameter i3 not passed"
    End If
    
    If IsMissing(i4) Then
        MsgBox "parameter i4 not passed"
    End If
    
End Function

 

[Hendy2322]

There are two ways I can think of:

Option 1:
You can declare optional parameters of any data type and provide a default value to be used if that parameter is omitted.

'Option 1
Function Read(i1 As Integer, Optional i2 As Integer = 9999, Optional i3 As Variant = 9999, Optional i4 As Variant = 9999)
    
    If i2 = 9999 Then
        MsgBox "Parameter i2 not passed"
    End If
    
    If i3 = 9999 Then
        MsgBox "Parameter i3 not passed"
    End If
    
    If i4 = 9999 Then
        MsgBox "parameter i4 not passed"
    End If
    
End Function

Option 2:
If you change the datatype of the Optional variables to Variant then you can use the IsMissing function to determine if the parameter was passed. It will return false for any other datatype, even if that parameter is declared as optional and is in fact missing. It also won't work if you assign a default value to the Optional Variant variable.

'Option 2
Function Read(i1 As Integer, Optional i2 As Variant, Optional i3 As Variant, Optional i4 As Variant)
    
    If IsMissing(i2) Then
        MsgBox "Parameter i2 not passed"
    End If
    
    If IsMissing(i3) Then
        MsgBox "Parameter i3 not passed"
    End If
    
    If IsMissing(i4) Then
        MsgBox "parameter i4 not passed"
    End If
    
End Function

Sorry, forgot to change the i3 and i4 variable datatypes to integer. Here is the correct code for Option 1:

'Option 1
Function Read(i1 As Integer, Optional i2 As Integer = 9999, Optional i3 As Integer = 9999, Optional i4 As Integer = 9999)
    
    If i2 = 9999 Then
        MsgBox "Parameter i2 not passed"
    End If
    
    If i3 = 9999 Then
        MsgBox "Parameter i3 not passed"
    End If
    
    If i4 = 9999 Then
        MsgBox "parameter i4 not passed"
    End If
    
End Function

 

[MetLife]

Thanks!