//题目：如下为类型CMyString的声明，请为该类型添加赋值运算符

 //以下为完整代码和测试用例

 #pragma warning(disable:4996)

 #include <iostream>

 #include <cstring>

 using namespace std;

 class CMyString {

 public:

     CMyString(char* pData = nullptr);

     CMyString(const CMyString& str);

     ~CMyString(void);

     // operator "="

     CMyString& operator =(const CMyString& str);

     void print();//用来输出测试结果

 private:

     char*m_pData;

 };

 //the defination of the constructor fun

 CMyString::CMyString(char* pData)

 {

     if (pData == nullptr)

         m_pData = new char[];

     m_pData[] = '\0';

 }

 CMyString::CMyString(const CMyString& str)

 {

     int len = strlen(str.m_pData);

     m_pData = new char[len + ];

     //m_pData(str.m_pData);

     strcpy(m_pData, str.m_pData);

 }

 CMyString::~CMyString()

 {

     //delete m_pData[];

     delete[]m_pData;

 }

 CMyString& CMyString:: operator =(const CMyString &str)

 {

     if (this == &str);

     return *this;

     delete[]m_pData;

     m_pData = nullptr;

     m_pData = new char[strlen(str.m_pData) + ];

     strcpy(m_pData, str.m_pData);

     return *this;

 }

 void CMyString:: print()

 {

     cout << m_pData << endl;

 }

 //测试用例

 void test1()

 {

     char* str = "Hello World!";

     CMyString str1(str);

     CMyString str2;

     str2 = str1;//call CMystring& operator=(const CMyString& str)

     cout << " str is : " << str << endl;

     //cout << "str2 is : " << str2.print() << endl;//没有重载<<运算符，还不能用

     cout << "after 赋值" <<"str2 is : "<< endl;

     str2.print();

  }

 void test2()//赋值给自己

 {

     char* str = "Hello world!";

     CMyString str1(str);

     str1=str1;

     cout << " str is : " << str << endl;

     cout << "after 赋值" << "str1 is : " << endl;

     str1.print();

 }

 void test3()//连续赋值

 {

     char* str = "Hello World!";

     CMyString str1(str);

     CMyString str2, str3;

     str3 = str2 = str1;

     cout << "str1 is : " << endl;

     str1.print();

     cout << "str2 is : " << endl;

     str2.print();

     cout << "str3 is : " << endl;

     str3.print();

 }

 int main()

 {

     test1();

     test2();

     test3();

     system("pause");

     return ;

 }