类模板的练习：数组类模板

Array.h

#ifndef __ARRAY_H__
#define __ARRAY_H__

#include <iostream>
using namespace std;

template <typename T>
class Array
{
	//重载输出数组 的<< 运算符
	friend ostream& operator<<(ostream &out, Array &a)
	{
		for (int i = 0; i < a.len; i++)
			out << a[i] << " ";
		return out;
	}
public:
	Array(int len = 0)//构造
	{
		if (len <= 0)
		{
			this->len = 0;
			m_p = NULL;
			return;
		}
		this->len = len;
		m_p = new T[len];
	}

	Array(const Array &a)//拷贝构造
	{
		if (a.len <= 0)
		{
			this->len = 0;
			m_p = NULL;
			return;
		}
		this->len = a.len;
		m_p = new T[a.len];
		for (int i = 0; i < len; i++)
			m_p[i] = a.m_p[i];
	}

	~Array()//析构
	{
		if (m_p != NULL)
			delete[] m_p;
		m_p = NULL;
		len = 0;
	}

	Array& operator=(const Array &a)//赋值重载
	{
		if (this != &a)
		{
			Array tmp = a;//开辟临时空间，调用拷贝构造复制a的值,如果开辟失败，不会往下执行，避免内部变量找不到原来的指向
			
			T *p = tmp.m_p;//开辟正常的情况下，一tmp为中转站交换a.m_p和this->m_p的指向
			tmp.m_p = m_p;//tmp_mp指向原先this_mp的指向，函数运行完后，编译器自动回收栈上空间
			m_p = p;		//避免内存泄漏

			len = a.len;//复制其余数据
		}

		return *this;
	}

	T& operator[](int index)// 数组下标重载
	{
		return m_p[index];
	}
private:
	int len;//数组长
	T *m_p;//数组指针
};


#endif //__ARRAY_H__

Array.cpp

#include <iostream>
#include "Array.h"
using namespace std;

int main1()
{
	Array<int> a(10);
	for (int i = 0; i < 10; i++)
		a[i] = i;
	cout << a << endl;

	Array<int> b = a;
	cout << b << endl;

	Array<int> c;
	c = a;
	cout << c << endl;

	Array<double> d(10);
	for (int i = 0; i < 10; i++)
		d[i] = 100.0/(i+1);
	cout << d << endl;

	return 0;
}


//类 的数组
class Student
{
	friend ostream& operator<< (ostream& out, Student &s);
public:
	Student(){}
	Student(int id, char *name)
	{
		this->id = id;
		this->name = name;
	}
private:
	int id;
	char *name;
};

//重载输出类的 <<运算符
ostream& operator<< (ostream& out, Student &s)
{
	out << "id = " << s.id << ", name = " << s.name << endl;
	return out;
}

int main2()
{
	//a是一个数组，里面放的是5个类
	Student a[5] = {
		Student(1, "小明1"),
		Student(2, "小明2"),
		Student(3, "小明3"),
		Student(4, "小明4"),
		Student(5, "小明5")
	};
	Array<Student> s(5); 

	//数组中存的是值，往数组里存数据是值的复制
	//会调用赋值运算符重载函数
	for (int i = 0; i < 5; i++)
	{
		s[i] = a[i];
	}
	cout << s << endl;
	return 0;
}

int main()
{
	Student *ps1 = new Student(1, "小明1");
	Student *ps2 = new Student(2, "小明2");
	Student *ps3 = new Student(3, "小明3");
	Student *ps4 = new Student(4, "小明4");
	Student *ps5 = new Student(5, "小明5");

	Array<Student*> s(5);
	s[0] = ps1;
	s[1] = ps2;
	s[2] = ps3;
	s[3] = ps4;
	s[4] = ps5;

	for (int i = 0; i < 5; i++)
		cout << *s[i] << endl;
	
	return 0;
}