字符串封装

MyString.h
#pragma once
#include<iostream>
using namespace std;

class MyString
{
public:
	friend ostream & operator<<(ostream &cout, const MyString &str);
	friend istream &operator>>(istream &cin, MyString &str);
	char &operator[](int index);
	MyString &operator=(const MyString &str);
	MyString operator+(const char *str);
	MyString operator+(MyString &str);
	bool operator==(MyString &str);
	MyString();
	MyString(const char *str);
	MyString(const MyString & str);
	~MyString();

private:
	char *pString;
	int m_Size;
};


//	左移运算符重载
ostream &operator<<(ostream &cout, const MyString &str);
ostream &operator>>(ostream &cin, MyString &str);

Mystring.cpp
#include "MyString.h"

ostream & operator<<(ostream &cout, const MyString &str)
{
	cout << str.pString;
	return cout;
}

std::istream & operator>>(istream &cin, MyString &str)
{
	if (str.pString != NULL)
	{
		delete[]str.pString;
		str.pString = NULL;
	}
	char buf[1024];
	cin >> buf;
	str.pString = new char[strlen(buf) + 1];
	strcpy_s(str.pString, strlen(buf) + 1, buf);
	str.m_Size = strlen(buf);
	return cin;
}


char &MyString::operator[](int index)
{
	return this->pString[index];
}

MyString & MyString::operator=(const MyString &str)
{
	if (this->pString != NULL)
	{
		delete[]this->pString;
		this->pString = NULL;
	}

	this->pString = new char[strlen(str.pString)+1];

	strcpy_s(this->pString, strlen(str.pString) + 1, str.pString);

	this->m_Size = strlen(str.pString) + 1;

	return *this;
}

MyString MyString::operator+(const char *str)
{
	int newsize = this->m_Size + strlen(str) + 1;

	char *temp = new char[newsize];  //	开辟的空间

	memset(temp, 0, newsize);

	strcat_s(temp,strlen(temp)+strlen(this->pString)+1,this->pString);
	strcat_s(temp,strlen(temp)+strlen(str)+1, str);

	MyString newString(temp);

	delete[]temp;

	return newString;
}

MyString MyString::operator+(MyString &str)
{
	int newsize = this->m_Size + strlen(str.pString) + 1;

	char *temp = new char[newsize];  //	开辟的空间

	memset(temp, 0, newsize);

	strcat_s(temp, strlen(temp) + strlen(this->pString) + 1, this->pString);
	strcat_s(temp, strlen(temp) + strlen(str.pString) + 1, str.pString);

	MyString newString(temp);

	delete[]temp;

	return newString;
}

bool MyString::operator==(MyString &str)
{
	return !(strcmp(this->pString, str.pString));
}

MyString::MyString()
{
	;
}

MyString::MyString(const char *str)
{
	this->pString = new char[strlen(str) + 1];
	strcpy_s(this->pString, strlen(str) + 1, str);
	this->m_Size = strlen(str);
}

MyString::MyString(const MyString & str)
{
	this->pString = new char[strlen(str.pString)+1];
	strcpy_s(this->pString, strlen(str.pString) + 1, str.pString);
	this->m_Size = strlen(str.pString) + 1;
}



MyString::~MyString()
{
	if (this->pString != NULL)
	{
		delete[]this->pString;
		this->pString = NULL;
	}
}

1.cpp
#include<iostream>
#include "MyString.h"

using namespace std;



void test01()
{
	/*MyString p1 = "党彦林";

	cout << p1 << endl;

	MyString p3(p1);

	cout << p3 << endl;

	cout << "请给p1字符串重新赋值" << endl;

	cin >> p1;

	cout << p1 << endl;

	cout << "p1的第一个字母" << p1[0] << endl;

	p1[0] = 'd';

	cout << "修改后p1的第一个字母" << p1[0] << endl;

	MyString p2 = "";

	p2 = p1;

	cout << p2 << endl;*/

	/*MyString p4 = "abc";

	MyString p5 = "def";

	MyString p6 = p4 + p5;
	
	cout << p6 << endl;*/

	MyString p1 = "abc";

	MyString p2 = "abd";

	if (p1 == p2)
	{
		cout << "p1和p2相等" << endl;
	}
	else
	{
		cout << "p1和p2不相等" << endl;
	}
}




int main()
{
	test01();
	system("pause");
	return 0;
}