Value assignment operator function, value assignment operator

Value assignment operator function, value assignment operator
Question: The following is a declaration of the type CMyString. Please add a value assignment operator function for this type.

1 class CMyString2 {3 public: 4 CMyString (char * pData = NULL); // constructor 5 CMyString (const CMyString & str); // copy constructor 6 ~ CMyString (); // destructor 7 private: 8 char * m_pData; // data field, character pointer 9 };

Pay attention to the following points: whether to declare the return value type as a reference of this type, and return the instance's own reference before the function ends. Whether to declare the input parameter type as a constant reference. Whether to release the memory of the instance. Determines whether the input parameter is the same as the current instance.

 1 #include "stdafx.h" 2 #include<string> 3 class CMyString 4 { 5 public: 6     CMyString(char* pData =  NULL); 7     CMyString(const CMyString& str); 8     ~CMyString(void); 9 10     CMyString& operator = (const CMyString& str);11 12     void Print();13 private:14     char* m_pData;15 };16 17 CMyString::CMyString(char* pData)18 {19     if(pData == NULL)20     {21         m_pData = new char[1];22         m_pData[0] = '\0';23     }24     else25     {26         int length = strlen(pData);27         m_pData = new char[length + 1];28         strcpy(m_pData, pData);29     }30 }31 32 CMyString::CMyString(const CMyString &str)33 {34     int length = strlen(str.m_pData);35     m_pData = new char[length + 1];36     strcpy(m_pData, str.m_pData);37 }38 39 CMyString::~CMyString()40 {41     delete[] m_pData;42 }43 44 CMyString& CMyString::operator = (const CMyString& str)45 {46     if(this == &str)47         return *this;48 49     delete []m_pData;50     m_pData = NULL;51 52     m_pData = new char[strlen(str.m_pData) + 1];53     strcpy(m_pData, str.m_pData);54 55     return *this;56 }57 58 void CMyString::Print()59 {60     printf("%s\n", m_pData);61 }62 63 int main()64 {65     char* text = "Hello world";66     CMyString str1(text);67     CMyString str2;68     str2 = str1;69 70     printf("The expected result is: %s.\n", text);71 72     printf("The actual result is: ");73     str2.Print();74     75     return 0;76 }