类和对象代码应用实践

实现一个String类

#include<string>
#include<iostream>
class String
{
public:
	String(const char* str = nullptr)//普通构造函数
	{
		std::cout << this << "String" << std::endl;
		if (str != nullptr)
		{
			m_data = new char[strlen(str) + 1];
			strcpy(this->m_data, str);
		}
		else
		{
			m_data = new char[1];
			*m_data = '\0';

		}
		
	}

	String(const String& other)
	{
		std::cout << this << "String(const String& other)" << std::endl;
		m_data = new char[strlen(other.m_data) + 1];
	     strcpy(m_data, other.m_data);
	}
	~String()
	{
		std::cout << this << "~String" << std::endl;
		delete[] m_data;
		m_data = nullptr;
	}
	String& operator=(const String& other)//赋值重载函数
	{
		std::cout << this << "String& operator=(const String& other)" << std::endl;
		//防止自赋值
		if (this == &other)
		{
			return *this;
		}
		//删除原有
		delete[] m_data;
		m_data = new char[strlen(other.m_data) + 1];
		strcpy(m_data, other.m_data);
		return *this;
	}
private:
	char* m_data;//用于保存字符串
};
int main()
{
	//调用const char* 参数的构造函数
	String str1;
	String str2("hello");
	String str3 = "world";

	//调用拷贝构造函数
	String str4 = str3;
	String str5(str3);

	//调用赋值重载函数
	//str1 = str2;
	str3 = str1 = str2;

	return 0;
}

输出信息

00000026FC7FF968String
00000026FC7FF988String
00000026FC7FF9A8String
00000026FC7FF9C8String(const String& other)
00000026FC7FF9E8String(const String& other)
00000026FC7FF968String& operator=(const String& other)
00000026FC7FF9A8String& operator=(const String& other)
00000026FC7FF9E8~String
00000026FC7FF9C8~String
00000026FC7FF9A8~String
00000026FC7FF988~String
00000026FC7FF968~String

循环队列实现

#include<string>
#include<iostream>
//循环队列
class Queue
{
public:
	Queue(int size = 20)
	{
		_pQue = new int[size];
		_front = _rear = 0;
		_size = size;
	}
	Queue(const Queue& src)
	{
		_size = src._size;
		_front = src._front;
		_rear = src._rear;
		_pQue = new int[_size];
		for (int i = _front; i != _rear; i = (i + 1) % _size)
		{
			_pQue[i] = src._pQue[i];
		}
	}

	Queue& operator=(const Queue& src)
	{
		if (this == &src)
		{
			return *this;
		}
		delete[] _pQue;
		_size = src._size;
		_front = src._front;
		_rear = src._rear;
		_pQue = new int[_size];
		for (int i = _front; i != _rear; i = (i + 1) % _size)
		{
			_pQue[i] = src._pQue[i];
		}
	}
	~Queue()
	{
		delete[] _pQue;
		_pQue = nullptr;
	}
	void push(int val)//入队操作
	{
		if (full())
			resize();
		_pQue[_rear] = val;
		_rear = (_rear + 1) % _size;

	}
	void pop()
	{
		if (empty())
			return;
		_front = (_front + 1) % _size;
	}
	int front()//获取队头元素
	{
		return _pQue[_front];
	}
	bool full() { return (_rear + 1) % _size == _front; }
	bool empty() { return _front == _rear; }
private:
	int* _pQue;//申请队列的数组空间
	int _front;//指示队头的位置 
	int _rear;//指向队尾的位置
	int _size;//队列扩容的总大小
	void resize()
	{
		int* ptmp = new int[2 * _size];
		int index = 0;
		for (int i = _front; i != _rear; i = (i + 1) % _size)
		{
			ptmp[index++] = _pQue[i];
		}
		delete[] _pQue;
		_pQue = ptmp;
		_front = 0;
		_rear = index;
		_size *= 2;
	}
};
int main()
{
	Queue queue;
	for (int i = 0; i < 20; ++i)
	{
		queue.push(rand() % 100);
	}
	Queue queue1 = queue;
	while (!queue.empty())
	{
		std::cout << queue.front() << " ";
		queue.pop();
	}
	std::cout << std::endl;


	while (!queue1.empty())
	{
		std::cout << queue1.front() << " ";
		queue1.pop();
	}
}

输出信息如下：

41 67 34 0 69 24 78 58 62 64 5 45 81 27 61 91 95 42 27 36
41 67 34 0 69 24 78 58 62 64 5 45 81 27 61 91 95 42 27 36