const，template，pointer，virtual

1. typdef 以及 typename 声明类型 时候，需要注意与const 使用时的 修饰作用。
2. //pointer operator, not allowed //error: invalid operands of types ‘int*’ and ‘int*’ to binary ‘operator+’【指针不能重载运算符】

#include <stdio.h>#include <stdlib.h>#include <iostream>#include <string>template <typename T>class base{public:    virtual void print(const T i)    { printf("base:: i=%x, *i=%x\n",i,*i);}};class baseDerived:public base<int*>{public://  void print(const int* i)  //not override//  { printf("baseDerived:: i=%x, *i=%x\n",i,*i);}    void print(int* const i)    { printf("baseDerived:: i=%x, *i=%x\n",i,*i);}};//pointer operator, not allowed //error: invalid operands of types 'int*' and 'int*' to binary 'operator+'//int* operator +(int* p1,int* p2)//{//  return  int*( (unsigned long)p1 +(unsigned long)p2 );//}int main(){    base<int*>* b1=new baseDerived;    baseDerived* d1=new baseDerived;    int p=10;    b1->print(&p);    d1->print(&p);     base<int*>* b2=new base<int*>;    b2->print(&p);    delete b1;    delete b2;    delete d1;}

template <typename T>class base{    T data;public:    base(){};    base(T num):data(num)    {}    virtual void print(const T i)    { printf("base:: i=%x, *i=%x\n",i,1);} //*i    virtual T operator +(T& other)    { printf("base:: operator+ %x + %x\n",data,other); return data+other;}};class baseDerived1:public base<int>{    int data;public:    baseDerived1(){}    baseDerived1(int num):data(num)    {}    int operator +(int& other)    { printf("base:: operator+ %x + %x\n",data,other); return data+other;}    void print(int* const i)    { printf("baseDerived:: i=%x, *i=%x\n",i,*i);}};int main(){    base<int>* b11=new baseDerived1(1);    baseDerived1* d11=new baseDerived1(2);    int oa=5;    printf("b11+5=%x\n",*b11+oa);    printf("d11+5=%x\n",*d11+oa);    base<int>* b12=new base<int>(5);    printf("b12+5=%x\n",*b12+oa);}