在C ++中将类变量地址初始化为NULL？

假设我有一个如下所示的类：

  class CBase
  {
      public:
         CBase(void){};
         ~CBase(void){};
         Sigintgen m_oSignals;// This is another class variable which i have not defined here.
   };

代码开始如下所示：

       main()
       {
           CBasec *ptr = new CBasec();
           I would want the following to happen as shown below:
           &(ptr->m_oSignals) should be equal to NULL. Can anyone please suggest me how to get this?
            &(ptr->m_oSignals) = NULL; //This was tried but compilation errors.    
       }

高级谢谢您的支持。