C++ 类继承的一个例子

#include <stdlib.h>
 #include <stdio.h>class A
 {
 public:
   A();
    ~A();
   virtual int funA(int a) = 0;
 };A::A()
 {
   printf("A constructor/n");
 }A::~A()
 {
     printf("A destructor /n");
 }class B : public A
 {
  public:
   B();
   ~B();
   int funA(int a);
   private:
     int t;
 };int B:: funA(int a)
  {
    
        t = a;
        printf(" t = %d /n " ,t );
        return t;
  }
  
  B::B()
  {
     printf("B constructor /n");
  }
  B::~B()
  {
     printf("B destructor /n");
  }
 int main()
 {
    A *  ta = new B();
   
    int t= ta->funA(123);
   
    delete ta;
   
    return 0;
 }