How do I pass a variable from one function to another function?

Question

I am trying to pass a variable from one function to another function.

My first thought is to use the ByRef declaration which I hear will pass arguments by reference in Visual Basic. I am unclear, however, on how to use it. Right now I have the following code.

            Function number(x As Double) As Double

                Dim z As Double
                z = 10.5
                number = x

            End Function

            Function triple(ByRef z As Double) As Double

                z = z * 3
                triple = z

            End Function

Lets say A1=2.5. If I say B1=number(A1) then the answer is 2.5 which I expected it to be. I then say B2=triple(B1) but then the answer is 7.5 instead of 31.5. I am not sure why it's taking the value of A1 instead of taking the value of the variable z from the function number.

Here's a screenshot of the worksheet

Thanks in advance.

Answer 1

The z inside the number function is gone by the time the function returns. The triple function just tipples the number passed, 2.5 times 3 which is what you are seeing. The tipple function has no idea of z. One way to share variables is to declare them outside of the functions. Dim z as double outside the function. But then if you pass z as the value of b1 which is 2.5 then you will get the same 7.5 just call triple, don't pass the value of b1

Dim z As Double

    Function tripple(x As Double)
        ' Use the value calculated from first function
        tripple = z * 3

    End Function
    Function number(x As Double)

        ' Set the global variable
        ' May be some calculations are done and z is set
        z = 10.5

        'Return x as in original code
        number = x
    End Function