5.C++构造 析构 拷贝 赋值函数

#include <iostream>
#include <string.h>

using namespace std;
class A
{
    
    
public:
    A(char *ps)
    {
    
    
        name = new char[strlen(ps) +1];
        len = strlen(ps);
        memcpy(name, ps, len);

        cout<<this<<" constructor A"<<endl;
    }

    A(const A& another)
    {
    
    
       len = strlen(another.name);
       name = new char[len +1];
       strcpy(name,another.name);
       cout<<this<<" copy A"<<endl;
    }

    A & operator=(const A & another)
    {
    
    
        cout<<this<<" = A"<<endl;
        if(this == &another)
            return *this;
        else
        {
    
    
            delete []this->name;
            int lens = strlen(another.name);
            this->name = new char[lens +1];
            strcpy(this->name, another.name);
            return *this;
        }
    }

    ~A()
    {
    
    
       cout<<this<<" destructor A"<<endl;
    }

    void dis()
    {
    
    
        cout<<len<<endl;
        cout<<name<<endl;
    }

private:
    int len;
    char *name;
};

int main()
{
    
    
    cout << "len " << strlen("helloworld") << endl;
    A a("helloworld");
    a.dis();

    A b(a);
    b.dis();

    A c = b;
    c.dis();

    A d("helloworld2");
    d = c;
    d.dis();

    return 0;
}