'Double型のダンプを取得する関数

'=DblDump5(0.1+0.2-0.3) などと使います。

Option Explicit

Type MyDouble1
    Value As Double
End Type

Type MyDouble2
    Value(0 To 3) As Integer
End Type

Function DblDump5(number As Double) As String
    Dim a As MyDouble1, b As MyDouble2
    Dim c As Long, d As Long
    Dim i As Integer, j As Integer, k As Integer
    Dim s As String * 64
    a.Value = number
    LSet b = a
    k = 64
    For i = 0 To 3
        c = b.Value(i)
        d = 1
        For j = 0 To 15
            If (c And d) = 0 Then
                Mid(s, k, 1) = "0"
            Else
                Mid(s, k, 1) = "1"
            End If
            k = k - 1
            d = d * 2
        Next
    Next
    DblDump5 = Mid$(s, 1, 1) & "-" & Mid$(s, 2, 11) & "-" & Mid$(s, 13)
End Function

Sub Test()
    Dim s As String
    s = DblDump5(0.1 + 0.2 - 0.3)
    MsgBox s, , "符号部 - 指数部 - 仮数部"
End Sub