How can I detect if my process is running UAC-elevated or not?

For those of us working in C#, in the Windows SDK there is a "UACDemo" application as a part of the "Cross Technology Samples". They find if the current user is an administrator using this method:

private bool IsAdministrator
{
    get
    {
        WindowsIdentity wi = WindowsIdentity.GetCurrent();
        WindowsPrincipal wp = new WindowsPrincipal(wi);

        return wp.IsInRole(WindowsBuiltInRole.Administrator);
    }
}

(Note: I refactored the original code to be a property, rather than an "if" statement)

I do not think elevation type is the answer you want. You just want to know if it is elevated. Use TokenElevation instead of TokenElevationType when you call GetTokenInformation. If the structure returns a positive value, the user is admin. If zero, the user is normal elevation.

Here is a Delphi solution:

function TMyAppInfo.RunningAsAdmin: boolean;
var
  hToken, hProcess: THandle;
  pTokenInformation: pointer;
  ReturnLength: DWord;
  TokenInformation: TTokenElevation;
begin
  hProcess := GetCurrentProcess;
  try
    if OpenProcessToken(hProcess, TOKEN_QUERY, hToken) then try
      TokenInformation.TokenIsElevated := 0;
      pTokenInformation := @TokenInformation;
      GetTokenInformation(hToken, TokenElevation, pTokenInformation, sizeof(TokenInformation), ReturnLength);
      result := (TokenInformation.TokenIsElevated > 0);
    finally
      CloseHandle(hToken);
    end;
  except
   result := false;
  end;
end;

The following C++ function can do that:

HRESULT GetElevationType( __out TOKEN_ELEVATION_TYPE * ptet );

/*
Parameters:

ptet
    [out] Pointer to a variable that receives the elevation type of the current process.

    The possible values are:

    TokenElevationTypeDefault - This value indicates that either UAC is disabled, 
        or the process is started by a standard user (not a member of the Administrators group).

    The following two values can be returned only if both the UAC is enabled
    and the user is a member of the Administrator's group:

    TokenElevationTypeFull - the process is running elevated. 

    TokenElevationTypeLimited - the process is not running elevated.

Return Values:

    If the function succeeds, the return value is S_OK. 
    If the function fails, the return value is E_FAIL. To get extended error information, call GetLastError().

Implementation:
*/

HRESULT GetElevationType( __out TOKEN_ELEVATION_TYPE * ptet )
{
    if ( !IsVista() )
        return E_FAIL;

    HRESULT hResult = E_FAIL; // assume an error occurred
    HANDLE hToken   = NULL;

    if ( !::OpenProcessToken( 
                ::GetCurrentProcess(), 
                TOKEN_QUERY, 
                &hToken ) )
    {
        return hResult;
    }

    DWORD dwReturnLength = 0;

    if ( ::GetTokenInformation(
                hToken,
                TokenElevationType,
                ptet,
                sizeof( *ptet ),
                &dwReturnLength ) )
    {
            ASSERT( dwReturnLength == sizeof( *ptet ) );
            hResult = S_OK;
    }

    ::CloseHandle( hToken );

    return hResult;
}