在 Excel VBA 中设置默认的 TextBox.Value TypeName

Question

I have a vba function that checks if a user-input from a text box is positive integer or not. The code below:

Public Function IsPosInteger(n As Variant) As Boolean  
    If IsNumeric(n) = True Then
        If (n = Int(n)) And n > 0 Then
            IsPosInteger = True
        Else
            IsPosInteger = False
        End If
    Else
        IsPosInteger = False
End If
End Function

The problem is that upon testing the function still returns false for a valid positive integer. Upon further investigation, I noticed that the variable type by default for texbox values is String. Probably the main reason why IsNumeric is returning false.

Function below is what I used to determine the type of the variable.

TypeName(n)

Answer 1

This worked for me.

I used an inputbox that contained:

• strings (False)
• negative numbers (False)
• positive numbers (true)
• positive numbers and letters (false)

Public Function IsPosInteger(n As Variant) As Boolean
    If n > 0 And IsNumeric(n) Then IsPosInteger = True
End Function

---

Now, the other issue may arise that the value n is still technically type String due to the nature of the inputbox -- even if it passes the test of this function. If you wish to change this behavior , continue reading.

To do this, ensure that you are using ByRef (when this is intentional , I usually type out ByRef on the argument, even though it is automatically assumed by VBA that any argument passed to a function is ByRef if it doesn't explicitly state ByVal ) .

If this is the outcome you are wanting, then you can use this function:

Public Function IsPosInteger(ByRef n As Variant) As Boolean
    If n > 0 And IsNumeric(n) Then 
        IsPosInteger = True
        n = clng(n) '<-- This converts the variant (currently a string) n to type long,
                    '    only if it passes the test
    end if
End Function

You must ensure that n in the calling routine is of type Variant , else you will encounter an error.

Answer 2

Public Function IsPosInteger(s As String) As Boolean 'boolean data type is false by default.
    If (IsNumeric(s) = False) Then Exit Function
    If (s < 1) Then Exit Function
    If (InStr(s, ".") = False) Then IsPosInteger = True
End Function

Function tests that the input is numeric, not less than 1, and does not contain a decimal. Here is an example of how you could use it in your calling sub:

Sub TestInput()
    Dim sUserInput As String
    Dim boolPositiveInt As Boolean
    Dim i As Integer

    sUserInput = Range("A1").Value2
    boolPositiveInt = IsPosInteger(sUserInput)
    If (boolPositiveInt = False) Then
        MsgBox "Invalid input. Please enter a positive integer"
        Exit Sub
    End If

    i = CInt(sUserInput)
    'continue working with integer variable here
End Sub