給類CMyString新增賦值運算子函式，初級做法如下:

#include<iostream>
#include<string.h>
using namespace std;

class CMyString{
	public:
		CMyString(const char *pData=NULL);
		~CMyString(void);
		CMyString& operator = (const CMyString &str);
		CMyString& operator = (const char *str);
		void show();
	private:
		char *m_pData;
	
};

CMyString::CMyString(const char *pData){
	if(pData == NULL){
		m_pData = new char[1];
		m_pData[0] = '\0';
		return;
	}
		
	m_pData = new char[strlen(pData)+1];
	memcpy(m_pData,pData,sizeof(pData));
}

void CMyString::show(){
	cout<<m_pData<<endl;
}

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

CMyString& CMyString::operator = (const CMyString &str){
	if(this == &str)  
        return *this;  
      
    delete []m_pData;  
    m_pData = NULL;   
      
    m_pData = new char[strlen(str.m_pData)+1];  
    strcpy(m_pData,str.m_pData);  
    return *this;  
}

CMyString& CMyString::operator = (const char *str){  
    if(str == NULL)  
        return *this; 
        
	delete []m_pData;
	m_pData = NULL;
	
    m_pData = new char[strlen(str)+1];  
    strcpy(m_pData,str); 
    return *this; 
} 



int main(){
	CMyString str1("love");
	str1.show();
	
	CMyString str2,str3;
	str3 = str2 = str1;
	str3.show();
	str2.show();
	
	CMyString str4;
	str4 = "haha";
	str4.show();

	CMyString str5("!!!");
	str5.show();
	
	return 0;
}
 

高階做法如下:

CMyString& CMyString::operator = (const CMyString &str){
	if(this != &str){
		CMyString strTmp(str);
		char *temp = strTmp.m_pData;
		strTmp.m_pData = m_pData;
		m_pData = temp;	
	}
	
	return *this;
}