假设有下面的类层次结构： classA { public : classB : publicA { private : char * bufer ;A0( cout <<" Awasborn !“:) virtual A0{ cout <<" Adiesout !";} public : B ( intlen ){ buffer = newchar [ len ]; cout <<＂ Bwasborn !";B0{ cout <<" Bdiesout !"<< endl ; delete [] buffer ;主函数如下：voidmain0B‘ pb = newB (100); A * pa = pb ; deletepa ;那么，执行结果应当是：