How to detect whether Vista UAC is enabled?

Question

I need my application to behave differently depending on whether Vista UAC is enabled or not. How can my application detect the state of UAC on the user\'s computer?

Answer 1

You can do it be examining the DWORD value EnableLUA in the following registry key:

HKLM/SOFTWARE/Microsoft/Windows/CurrentVersion/Policies/System

If the value is 0 (or does not exist) then the UAC is OFF. If it's present and non-zero, then UAC is ON:

BOOL IsUacEnabled( )
{
    LPCTSTR pszSubKey = _T("SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Policies\\System");
    LPCTSTR pszValue = _T("EnableLUA");
    DWORD dwType = 0;
    DWORD dwValue = 0;
    DWORD dwValueSize = sizeof( DWORD );

    if ( ERROR_SUCCESS != SHGetValue( HKEY_LOCAL_MACHINE, pszSubKey, pszValueOn, 
        &dwType, &dwValue, &dwValueSize) )
    {
            return FALSE;
    }

    return dwValue != 0;
} 

Note that if the user has changed the state of UAC but has not restarted the computer yet, this function will return an inconsistent result.