CodeItBetter Programming Another VB Programming Blog

'System & API - How to Get current user Name (in three ways)
'1. Using the Environment Variable:

'   Using the environment variables are easy to use but unreliable for these reasons -
'       1. The user can edit the value to anything they want by going to the 
'          System Properties and changing the values.
'       2. The user can delete the environment variables too.
'       3. Another thing that is important to note is that this variable is not set 
'          by default on Win9x/Me.
'
'   To get the username this way is simple:

Option Explicit
 
Private Sub Command1_Click()
    MsgBox Environ("USERNAME")
End Sub
 
 
'2. Using the API:

'   There are two APIs that can retrieve the user name.

'   (i) GetEnvironmentVariable API:

'   It is just another way to read an environment variable (and as such, 
'   has the same problems mentioned above).

Option Explicit
 
Private Declare Function GetEnvironmentVariable Lib "kernel32" Alias "GetEnvironmentVariableA" _
    (ByVal lpName As String, ByVal lpBuffer As String, ByVal nSize As Long) As Long
 
Private Sub Command1_Click()
    Dim strUserName As String * 255    'Create a string buffer of 255 chars in length
    Dim X As Integer
 
    X = GetEnvironmentVariable("USERNAME", strUserName, Len(strUserName))
    If X > 0 Then
        'Look for Null Character, usually included
        X = InStr(strUserName, vbNullChar)
        'Trim off buffered spaces too
        If X > 0 Then
            MsgBox (Left$(strUserName, X - 1))
        Else
            MsgBox (Left$(strUserName, X))
        End If
    End If
End Sub
 
'   (ii) The GetUserName API:

'   It is probably the most reliable and secure way to retrieve the username. 
'It cannot be changed by the user as long as Windows permissions dissallow it.

'If placed in a module it will be available to all forms in your project for calling
'Inside Module1.bas
Option Explicit
 
Private Declare Function GetUserName Lib "advapi32.dll" Alias "GetUserNameA" _
    (ByVal lpBuffer As String, nSize As Long) As Long
 
Public Function CurrentUser() As String
    '* Function to get the current logged on user in windows *
    Dim strBuff As String * 255
    Dim X As Long
 
    CurrentUser = ""
    X = GetUserName(strBuff, Len(strBuff) - 1)
    If X > 0 Then
        'Look for Null Character, usually included
        X = InStr(strBuff, vbNullChar)
        'Trim off buffered spaces too
        If X > 0 Then
            CurrentUser = UCase(Left$(strBuff, X - 1))    'UCase is optional
        Else
            CurrentUser = UCase(Left$(strBuff, X))
        End If
    End If
End Function
 
'Sample usage:
'Behind Form1.frm (or whatever your form's name is)
Option Explicit
 
Private Sub Form_Load()
    MsgBox CurrentUser
End Sub
 
'Another way is:

Private Enum EXTENDED_NAME_FORMAT
    NameUnknown = 0
    NameFullyQualifiedDN = 1
    NameSamCompatible = 2
    NameDisplay = 3
    NameUniqueId = 6
    NameCanonical = 7
    NameUserPrincipal = 8
    NameCanonicalEx = 9
    NameServicePrincipal = 10
End Enum
 
Private Declare Function GetUserNameEx Lib "secur32.dll" Alias "GetUserNameExA" _
    (ByVal NameFormat As EXTENDED_NAME_FORMAT, ByVal lpNameBuffer As String, _
    ByRef nSize As Long) As Long
 
Private Sub Command1_Click()
    Dim sBuffer As String, Ret As Long
    sBuffer = String(256, 0)
    Ret = Len(sBuffer)
    If GetUserNameEx(NameSamCompatible, sBuffer, Ret) <> 0 Then
        MsgBox "Username: " + Left$(sBuffer, Ret)
    Else
        MsgBox "Error while retrieving the username"
    End If
End Sub
 
'Please note that this method requires Windows 2000 or later and does work with XP.