关于模版子类初始化模版父类，调用父类成员问题（解决）以及运算符重载什么时候用

#include<iostream>
using namespace std;

template <typename T>
class Parent
{
public:
	Parent(T p1)
	{
		this->p1 = p1;
	}
	void printP()
	{
		cout << "p1==" << p1 << endl;
	}
protected:
	T p1;
};
template <typename U>
class Child : public  Parent <U>//这里的<>在parent前后都可以
{
public:
	Child(U c1, U tem) :Parent <U> (tem)
	{
		this->c1 = c1;
		
	}
	void printC()
	{
		cout << " c1 = " << c1 << " tem = " << tem << endl;//不理解这里为什么会出现错误？
	}
private:
	U c1;
};

class B:public Parent<int>
{
public:
	B(int b1, int p):Parent(p)
	{
		this->b1 = b1;
	}
	void printB()
	{
		cout << " b1 = " << b1 << " p1 = " << p1 << endl;
	}
private:
	int b1;

};
int main()
{
	Child<int> h1(1, 3);
	h1.printC();
	h1.printP();
	cout << " 我是漂亮的分割线\n";
	B b1(2,5);
	b1.printB();
	b1.printP();
	cout << " 我是漂亮的分割线\n";
	Parent <char> a1('d');
	a1.printP();

	system("pause");
}

　　结果显示： error C2065: “tem”: 未声明的标识符

 

　　

#include<iostream>
using namespace std;

template <typename T>
class Parent
{
public:
	Parent(T p1=0)
	{
		this->p1 = p1;
	}
	void printP()
	{
		cout << "p1==" << p1 << endl;
	}
	friend ostream & operator << (ostream &out, Parent & e1);
	
protected:
	T p1;
};
ostream & operator<<(ostream &out, Parent<int> & e1)
{
	out << e1.p1;
	return out;
}
template <typename U>
class Child : public  Parent <U>//这里的<>在parent前后都可以
{
public:
	Child(U c1, U tem) :tem (tem)
	{
		this->c1 = c1;
		
	}
	void printC()
	{
		//因为这里的tem是父类的对象，打印对象的时候应该是tem。什么什么，之类的而不是直接打印tem

		cout << " c1 = " << c1 << " tem = " << tem << endl;//不理解这里为什么会出现错误？
还是存在疑问，这里什么时候能够直接调用tem参数呢，而不是对象？
	}
private:
	U c1;
	Parent<U> tem;
};

//class B :public Parent<int>
//{
//public:
//	B(int b1, int p) :Parent(p)
//	{
//		this->b1 = b1;
//	}
//	void printB()
//	{
//		cout << " b1 = " << b1 << " p1 = " << p1 << endl;
//	}
//private:
//	int b1;
//
//};
int main()
{
	Child<int> h1(1, 3);
	h1.printC();
	h1.printP();
	cout << " 我是漂亮的分割线\n";
	/*B b1(2,5);
	b1.printB();
	b1.printP();*/
	cout << " 我是漂亮的分割线\n";
	Parent <char> a1('d');
	a1.printP();

	system("pause");
}

　　

#include<iostream>
using namespace std;

template <typename T>
class Parent
{
public:
	Parent(T p1)
	{
		this->p1 = p1;
	}
	void printP()
	{
		cout << "p1==" << p1 << endl;
	}
	friend ostream & operator << (ostream &out, Parent & e1);
	
public:
	T p1;
};
ostream & operator<<(ostream &out, Parent<int> & e1)
{
	out << e1.p1;
	return out;
}
template <typename U>
class Child : public  Parent <U>//这里的<>在parent前后都可以
{
public:
	Child(U c1, U tem) :Parent<U> (tem)
	{
		this->c1 = c1;
		//this->p1 = tem;
	}
	void printC()
	{
		//这个是傻子，你给p1赋值为tem，tem相当于一个字面量，怎么可以输出一个字面量呢？昨晚肯定晕了。
		//cout << " c1 = " << c1 << " tem = " << tem << endl;//不理解这里为什么会出现错误？
		cout << " c1 = " << c1 << " p1 = " << p1 << endl;
		
	}
private:
	U c1;
	
};

class B :public Parent<int>
{
public:
	B(int b1, int p) :Parent<int>(p)
	{
		this->b1 = b1;
	}
	void printB()
	{
		cout << " b1 = " << b1 << " p1 = " << p1 << endl;
	}
private:
	int b1;

};
class Test
{
public:
	Test(int t1)
	{
		this->t1 = t1;
	}
	void printT()
	{
		cout << t1 << endl;
	}
public:
	int t1;
};
int main()
{
	Child<int> h1(1, 3);
	cout<<h1.p1;
	h1.printC();
	h1.printP();
	cout << " 我是漂亮的分割线\n";
	B b1(2,5);
	cout<<b1.p1;
	b1.printB();
	b1.printP();
	cout << " 我是漂亮的分割线\n";
	Parent <char> a1('d');
	a1.printP();
	cout << " 我是漂亮的分割线\n";
	Test t(2);
	cout<<t.t1;
	system("pause");

}