const 成员函数（4）

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#include <iostream> 

using namespace std;
class base1
{
    public:
        virtual void fun1a() const = 0;  //纯虚函数，该类为抽象类
        void fun1a() const;              //error: 'void base1::fun1a() const' cannot be overloaded
        void fun1b();
    protected:
        int var1a;
};
class base2: public base1
{
    public:
        virtual void fun1a() const
        {
            var2a = 0;                    //只读成员函数能修改由mutable
                                          //修饰的外部变量的值
            int _var_temp = 0;
        }
        void fun2b();
    protected:
        mutable int var2a;
};
int main()
{
    base2 b0;  
    return 0;
}

转载于:https://my.oschina.net/libowen/blog/91458