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;
}