A>class CSettings
A>{
A>    static CSettings * s_pSettings = NULL;
A>};
A>

The declaration of a static data member in its class definition is not a definition and may be of an incomplete type other than cv-qualified void. The definition for a static data member shall appear in a namespace scope enclosing the member’s class definition. In the definition at namespace scope, the name of the static data member shall be qualified by its class name using the :: operator.

class CSettings
{
    static CSettings * s_pSettings;
};

CSettings* CSettings::s_pSettings = NULL;