1.浅拷贝-shallow copy

#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <iostream>
using namespace std;
class MyString
{
    public:
        MyString(const char *str = "")
        {
            if(str == NULL)
            {
                data = new char[1];
                data[0] = '\0';
            }
            else
            {
                data = new char[strlen(str)+1];
                strcpy(data,str);
            }
            
        }
        ~MyString()
        {
            cout << "~MyString " << data << endl;
            delete []data;
            data = NULL;
        }
    public:
        char* data;
};
int main()
{
    MyString s1("hello");
    MyString s2 = s1;
    cout << "s1.data's address is " << (void*)(s1.data) << endl;
    cout << "s2.data's address is " << (void*)(s2.data) << endl;
}

2.深拷贝-deep copy

#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <iostream>
using namespace std;
class MyString
{
    public:
        MyString(const char *str = "")
        {
            if(str == NULL)
            {
                data = new char[1];
                data[0] = '\0';
            }
            else
            {
                data = new char[strlen(str)+1];
                strcpy(data,str);
            }
            
        }
        MyString(const MyString& s)
        {
            data = new char[strlen(s.data)+1];
            strcpy(data,s.data);
        }
        
        MyString& operator=(const MyString& s)
        {
            if(this!= &s)
            {
                delete []data;
                data = new char[strlen(s.data) + 1];
                strcpy(data,s.data);
            }
            return *this;
        }
        

        ~MyString()
        {
            cout << "~MyString " << data << endl;
            delete []data;
            data = NULL;
        }
    public:
        char* data;
};
int main()
{
    MyString s1("hello");
    MyString s2 = s1;
    cout << "s1.data's address is " << (void*)(s1.data) << endl;
    cout << "s2.data's address is " << (void*)(s2.data) << endl;
    MyString s3;
    cout << "s3.data's address is " << (void*)(s3.data) << endl;
    s3 = s2;
    cout << "s3.data's address is " << (void*)(s3.data) << endl;

}