面试题1：赋值运算符函数

/*
AssignmentOperator Definition
Created by taotao man on 2015-7-29
brief:  题目：如下为类型CMyString 的声明， 请为该类型添加赋值运算符函数
// 修改记录
add SetA();
change GetA();
*/

#include "stdafx.h"
#include <string>

class CMyString
{
public:
CMyString(char *pData = NULL);
CMyString(const CMyString&  str);
~CMyString(void);

void Print();

CMyString &operator = (const CMyString &str);

private:
char*	m_pData;

};

CMyString::CMyString(char *pData)
{
if(pData == NULL)
{
m_pData = new char[1];
}
else
{
int length = strlen(pData);
m_pData = new char[length + 1];
strcpy(m_pData, pData);
}
}

CMyString::CMyString(const CMyString &str)
{
int length = strlen(str.m_pData);
m_pData = new char[length + 1];
strcpy(m_pData, str.m_pData);
}

CMyString::~CMyString()
{
delete[]m_pData;
}

CMyString & CMyString::operator = (const CMyString &str)
{
if(this == &str)
return *this;
if(this != &str)	// 考虑异常安全性的解法
{
CMyString strTemp(str);

char *pTemp = strTemp.m_pData;
strTemp.m_pData = m_pData;
m_pData = pTemp;

}
delete []m_pData;	// 释放实例m_pData的内存
m_pData = NULL;

m_pData = new char[strlen(str.m_pData) + 1];
strcpy(m_pData, str.m_pData);
return *this;
}

// ====================测试代码====================

void CMyString::Print()
{
printf("%s", m_pData);
}

void Test1()	// 把一个CMyString 的实例赋值给另外意个实例
{
printf("Test1 begins:\n");
char *text = "Hello world";

CMyString str1(text);
CMyString str2;

str2 = str1;
printf("The expected result is : %s.\n", text);
printf("The actual result is:");
str2.Print();

system("pause");
}

void Test2()	// 把一个CMyString的实例赋值给它自己
{
printf("Test2 begins:\n");

char *text = "Hello world";
CMyString str1(text);
str1 = str1;
printf("The expected result is : %s.\n", text);
printf("The actual result is:");
str1.Print();
system("pause");
printf(".\n");
}

// 连续赋值

void Test3()
{
printf("Test3 begins:\n");
char *text = "Hello world";

CMyString str1(text);
CMyString str2, str3;
str3 = str2 = str1;
printf("The expected result is: %s.\n", text);
printf("The actual result is :");
str2.Print();
printf(".\n");

printf("The expected result is: %s.\n", text);
printf("The actual result is :");

str3.Print();
printf(".\n");

system("pause");
}

int _tmain(int argc, _TCHAR *argv[])
{
// Test1();
// Test2();
Test3();

return 0;

system("pause");
}