"VBA: Left-Hand Side Function Call Must Return Variant"

When working with VBA (Visual Basic for Applications), you might encounter an error that reads "VBA function call on left hand side of assignment must return variant". This error can be quite puzzling, especially for those new to VBA. Let's delve into understanding this error, its causes, and how to resolve it.

Understanding the Error

The error "VBA function call on left hand side of assignment must return variant" typically occurs when you're trying to assign the result of a function to a variable, but the function doesn't return a variant data type. In VBA, a function must return a value, and that value must be a variant data type if it's being assigned to a variable.

Causes of the Error

This error can be caused by a few different scenarios:

• Non-Variant Return Type: The function you're calling returns a data type other than Variant, such as Integer, String, or Boolean.
• No Return Statement: The function doesn't have a return statement at all, or it has an incorrect return statement.
• Incorrect Use of ByRef: If you're using the ByRef keyword incorrectly, it can also cause this error.

Example: Non-Variant Return Type

Here's a simple example that might trigger this error:

Function DivideByTwo(ByVal num As Integer) As Integer
    DivideByTwo = num / 2
End Function

Sub TestFunction()
    Dim result As Variant
    result = DivideByTwo(10) ' This will cause the error
End Sub

In this example, the function DivideByTwo returns an Integer, but we're trying to assign it to a Variant variable (result). This causes the error.

Resolving the Error

To fix this error, you need to ensure that the function you're calling returns a Variant data type. Here are a few ways to do this:

• Change the Return Type: If possible, change the return type of the function to Variant.
• Use CType or Variant: If you can't change the return type of the function, you can use the CType function or declare the variable as Variant.
• Check the Return Statement: Ensure that the function has a correct return statement.

Example: Changing the Return Type

Here's how you can modify the previous example to fix the error:

Function DivideByTwo(ByVal num As Integer) As Variant
    DivideByTwo = num / 2
End Function

Sub TestFunction()
    Dim result As Variant
    result = DivideByTwo(10) ' This will no longer cause the error
End Sub

Final Thoughts

The "VBA function call on left hand side of assignment must return variant" error can be a bit confusing, but understanding the cause and how to resolve it can help you avoid it in the future. Always ensure that the function you're calling returns a Variant data type when assigning it to a variable.