Private Declare Function GUN Lib "advapi32.dll" Alias "GetUserNameA" (ByVal myPara As String, myLen As Long) As Long

Public Function ActiveUserName() As String
'Benutzernamen auslesen
Dim AUN As String * 100
Dim AunLen As Byte
'100 Zeichen reichen in den meisten Fällen aus
AunLen = 100
If GUN(AUN, Len(AUN)) Then
    ActiveUserName = Left(AUN, AunLen)
Else
    ActiveUserName = "User can not be Identified"
End If
MsgBox ActiveUserName
End Function

Option Explicit

Private Declare Function GetUserName Lib "advapi32.dll" Alias "GetUserNameA" ( _
    ByVal lpBuffer As String, nSize As Long) As Long

 Sub name()
    Dim lngErgebnis As Long
    Dim lngPuffer As Long
    Dim strPuffer As String
    Dim strUser As String
    Dim strUsername As String
    lngPuffer = 255
    strUser = Space$(lngPuffer)
    lngErgebnis = GetUserName(strUser, lngPuffer)
    If lngErgebnis <> 0 Then
        strUsername = Left(strUser, lngPuffer - 1)
        Range("A1").Value = Trim$(strUsername)
    End If
End Sub

Public Function Angemeldet() As String
Angemeldet = Environ("USERNAME")
End Function