Excel VBA如何将双精度四舍五入为整数？

Question

I am trying to understand the type of errors that could happen when a wrong type of variable is declared in VBA.

This is the code I am using:

Sub testTypes()

Dim test1 As Integer
test1 = 0.5

Debug.Print test1

End Sub

I tried to use Double number types on purpose to see how VBA will round them (up or down) to make them an Integer, given that the number ends on .5

I got puzzling results:

5.567 --> 6
5.5 --> 6
4.5 --> 4
3.5 --> 4
2.5 --> 2
1.5 --> 2
0.5 --> 0

Could anyone explain how Excel determines whether it will round up or down?

Answer 1

In order to avoid so called banker's rounding (= midpoint value 5 always rounds to the nearest even number ) you can use

• (1) WorkSheetFunction.Round
• (2) a user defined function.

Banker's rounding is a standard form of rounding used in financial and statistical operations in order to minimize significant rounding errors over multiple rounding operations by consistently rounding midpoint values in a single direction.

(1) Example using the WorksheetFunction Round()

Sub RoundWithWorkSheetFunction()
' Purpose: avoid so called bankers' rounding in VBA (5 always rounds even)
With WorksheetFunction
    Debug.Print "WorksheetFunction.Round(3.5, 0)=" & .Round(3.5, 0), ":| VBA rounds to " & Round(3.5, 0)
    Debug.Print "WorksheetFunction.Round(4.5, 0)=" & .Round(4.5, 0), ":| VBA rounds to " & Round(4.5, 0)
End With

End Sub

(2) An alternative to the worksheet function (avoiding bankers' rounding):

Function roundIt(ByVal d As Double, ByVal nDigits As Integer) As Double
' Purpose: avoid so called bankers' rounding in VBA (5 always rounds even)
If nDigits > 0 Then
   ' if continental european colon instead of point separartor
   ' roundIt= val(Replace(Format(d, "0." & String(nDigits, "0")), ",", "."))
     roundIt = Val(Format(d, "0." & String(nDigits, "0")))
Else
   ' if continental european colon instead of point separartor
   ' roundIt =  val(Replace(Format(d / (10 ^ nDigits), "0."), ",", "."))
   roundIt = Val(Format(d / (10 ^ nDigits), "0."))
End If
End Function

Answer 2

Sandra, it will round up or down depending if it is an even or odd number. If it is an even number, it will be round down. Otherwise, it will round up.