Retrieve the Computer Name from the registry

How to search the registry for your Computer Name. You can adapt to search for any Known Key/Value. Place the following code in a form

Private Sub cmdGetComputerName_Click()
   QueryValue HKEY_LOCAL_MACHINE, "System\CurrentControlSet\Control\ComputerName\ComputerName", "ComputerName"
End Sub

Private Sub QueryValue(Where As Long, sKeyName As String, sValueName As String)
   Dim lRetVal As Long         'result of the API functions
   Dim hKey As Long         'handle of opened key
   Dim vValue As Variant      'setting of queried value

   lRetVal = RegOpenKeyEx(Where, sKeyName, 0, KEY_QUERY_VALUE, hKey)
   lRetVal = QueryValueEx(hKey, sValueName, vValue)
   MsgBox vValue
   RegCloseKey (hKey)
End Sub

Next, add this code to a module.

Public Const REG_SZ As Long = 1
Public Const REG_DWORD As Long = 4

Public Const HKEY_CLASSES_ROOT = &H80000000
Public Const HKEY_CURRENT_USER = &H80000001
Public Const HKEY_LOCAL_MACHINE = &H80000002
Public Const HKEY_USERS = &H80000003

Public Const ERROR_NONE = 0
Public Const ERROR_BADDB = 1
Public Const ERROR_BADKEY = 2
Public Const ERROR_CANTOPEN = 3
Public Const ERROR_CANTREAD = 4
Public Const ERROR_CANTWRITE = 5
Public Const ERROR_OUTOFMEMORY = 6
Public Const ERROR_ARENA_TRASHED = 7
Public Const ERROR_ACCESS_DENIED = 8
Public Const ERROR_INVALID_PARAMETERS = 87
Public Const ERROR_NO_MORE_ITEMS = 259

Public Const KEY_QUERY_VALUE = &H1
Public Const KEY_SET_VALUE = &H2
Public Const KEY_ALL_ACCESS = &H3F

Public Const REG_OPTION_NON_VOLATILE = 0

Declare Function RegCloseKey Lib "advapi32.dll" _
(ByVal hKey As Long) As Long
Declare Function RegCreateKeyEx Lib "advapi32.dll" Alias _
"RegCreateKeyExA" (ByVal hKey As Long, ByVal lpSubKey As String, _
ByVal Reserved As Long, ByVal lpClass As String, ByVal dwOptions _
As Long, ByVal samDesired As Long, ByVal lpSecurityAttributes _
As Long, phkResult As Long, lpdwDisposition As Long) As Long
Declare Function RegOpenKeyEx Lib "advapi32.dll" Alias _
"RegOpenKeyExA" (ByVal hKey As Long, ByVal lpSubKey As String, _
ByVal ulOptions As Long, ByVal samDesired As Long, phkResult As _
Long) As Long
Declare Function RegQueryValueExString Lib "advapi32.dll" Alias _
"RegQueryValueExA" (ByVal hKey As Long, ByVal lpValueName As _
String, ByVal lpReserved As Long, lpType As Long, ByVal lpData _
As String, lpcbData As Long) As Long
Declare Function RegQueryValueExLong Lib "advapi32.dll" Alias _
"RegQueryValueExA" (ByVal hKey As Long, ByVal lpValueName As _
String, ByVal lpReserved As Long, lpType As Long, lpData As _
Long, lpcbData As Long) As Long
Declare Function RegQueryValueExNULL Lib "advapi32.dll" Alias _
"RegQueryValueExA" (ByVal hKey As Long, ByVal lpValueName As _
String, ByVal lpReserved As Long, lpType As Long, ByVal lpData _
As Long, lpcbData As Long) As Long
Declare Function RegSetValueExString Lib "advapi32.dll" Alias _
"RegSetValueExA" (ByVal hKey As Long, ByVal lpValueName As String, _
ByVal Reserved As Long, ByVal dwType As Long, ByVal lpValue As _
String, ByVal cbData As Long) As Long
Declare Function RegSetValueExLong Lib "advapi32.dll" Alias _
"RegSetValueExA" (ByVal hKey As Long, ByVal lpValueName As String, _
ByVal Reserved As Long, ByVal dwType As Long, lpValue As Long, _
ByVal cbData As Long) As Long

Public Function SetValueEx(ByVal hKey As Long, sValueName As String, _
lType As Long, vValue As Variant) As Long
   Dim lValue As Long
   Dim sValue As String
   Select Case lType
       Case REG_SZ
           sValue = vValue & Chr$(0)
           SetValueEx = RegSetValueExString(hKey, sValueName, 0&, _
                                          lType, sValue, Len(sValue))
       Case REG_DWORD
           lValue = vValue
           SetValueEx = RegSetValueExLong(hKey, sValueName, 0&, _
lType, lValue, 4)
       End Select
End Function

Function QueryValueEx(ByVal lhKey As Long, ByVal szValueName As _
String, vValue As Variant) As Long
   Dim cch As Long
   Dim lrc As Long
   Dim lType As Long
   Dim lValue As Long
   Dim sValue As String

   On Error GoTo QueryValueExError

   ' Determine the size and type of data to be read
   lrc = RegQueryValueExNULL(lhKey, szValueName, 0&, lType, 0&, cch)
   If lrc <> ERROR_NONE Then Error 5

   Select Case lType
       ' For strings
       Case REG_SZ:
           sValue = String(cch, 0)

lrc = RegQueryValueExString(lhKey, szValueName, 0&, lType, _
sValue, cch)
           If lrc = ERROR_NONE Then
               vValue = Left$(sValue, cch - 1)
           Else
               vValue = Empty
           End If
       ' For DWORDS
       Case REG_DWORD:
lrc = RegQueryValueExLong(lhKey, szValueName, 0&, lType, _
lValue, cch)
           If lrc = ERROR_NONE Then vValue = lValue
       Case Else
           'all other data types not supported
           lrc = -1
   End Select

QueryValueExExit:
   QueryValueEx = lrc
   Exit Function

QueryValueExError:
   Resume QueryValueExExit
End Function