一个C++小程序出了错误帮改下

//base1.h
#ifndef BASE1_H
#define BASE1_H

class base1{
public:
base1(int x){value = x;}
int getbase1()const{return value;}

protected:
int value;
};

#endif
//base2.h
#ifndef BASE2_H
#define BASE2_H

class base2{
public:
base2(char c){letter = c;}
char getbase2()const{return letter;}
protected:
char letter;
};

#endif
//derived.h
#include "base1.h"
#include "base2.h"
#include <iostream>

using namespace std;

#ifndef DERIVED_H
#define DERIVED_H

class derived:public base1,public base2{
friend ostream &operator<<(ostream &,const derived &);
public:
derived(int,char,double); //这里出问题才编译不过的
protected:
double real;
};

#endif
//derived.cpp
#include "derived.h"
#include &l