Change Date Format of System using VB 6.0

If you want to change date format of your system to "dd/MM/yy" format:
First add the below code to Module name "modTime":

Option Explicit


Public Const LOCALE_SLANGUAGE As Long = &H2
Public Const LOCALE_SSHORTDATE As Long = &H1F

Public Const DATE_LONGDATE As Long = &H2
Public Const DATE_SHORTDATE As Long = &H1

Public Const HWND_BROADCAST As Long = &HFFFF&
Public Const WM_SETTINGCHANGE As Long = &H1A

Public Declare Function PostMessage Lib "user32" _
Alias "PostMessageA" _
(ByVal hwnd As Long, _
ByVal wMsg As Long, _
ByVal wParam As Long, _
lParam As Any) As Long

Public Declare Function EnumDateFormats Lib "kernel32" _
Alias "EnumDateFormatsA" _
(ByVal lpDateFmtEnumProc As Long, _
ByVal Locale As Long, _
ByVal dwFlags As Long) As Long

Public Declare Sub CopyMemory Lib "kernel32" _
Alias "RtlMoveMemory" _
(Destination As Any, _
Source As Any, _
ByVal Length As Long)

Public Declare Function GetSystemDefaultLCID Lib "kernel32" () As Long

Public Declare Function GetLocaleInfo Lib "kernel32" _
Alias "GetLocaleInfoA" _
(ByVal Locale As Long, _
ByVal LCType As Long, _
ByVal lpLCData As String, _
ByVal cchData As Long) As Long

Public Declare Function SetLocaleInfo Lib "kernel32" _
Alias "SetLocaleInfoA" _
(ByVal Locale As Long, _
ByVal LCType As Long, _
ByVal lpLCData As String) As Long


Public Function fGetUserLocaleInfo(ByVal lLocaleID As Long, _
ByVal lLCType As Long) As String

Dim sReturn As String
Dim lReturn As Long
lReturn = GetLocaleInfo(lLocaleID, lLCType, sReturn, Len(sReturn))
If lReturn Then

sReturn = Space$(lReturn)
If lReturn Then
fGetUserLocaleInfo = Left$(sReturn, lReturn - 1)
End If
End If

End Function


Public Function theEnumDates(lDateFormatString As Long) As Long
theEnumDates = 1
End Function


Private Function GetStrFromPointer(sString As Long) As String
Dim lPos As Long
Dim sBuffer As String
sBuffer = Space$(128)
Call CopyMemory(ByVal sBuffer, sString, ByVal Len(sBuffer))
lPos = InStr(sBuffer, Chr$(0))

If lPos Then
GetStrFromPointer = Left$(sBuffer, lPos - 1)
End If
End Function




Then Add Form with Command Button and add the below code in Button_click event:

Dim xCID As Long
Dim xChangedFormat As String

xCID = GetSystemDefaultLCID()

xChangedFormat = "dd/MM/yy"

If xChangedFormat <> "" Then

Call SetLocaleInfo(xCID, LOCALE_SSHORTDATE, xChangedFormat)

Call PostMessage(HWND_BROADCAST, WM_SETTINGCHANGE, 0&, ByVal 0&)

Call EnumDateFormats(AddressOf theEnumDates, xCID, DATE_SHORTDATE)
End If