4月25日 C++day3

#include <iostream>
using namespace std;

class Person
{
    const string name;
    int age;
    char sex;
public:
    Person():name("lisi")
    {cout << "Person无参构造" << endl;}
    Person(string name,int age,char sex):name(name),age(age),sex(sex)
    {cout << "Person有参构造" << endl;}
    void show()
    {
        cout <<"person的show:"<< name << age << sex <<endl;
    }
    Person(const Person &other):name(other.name)
    {
        this->age = other.age;
        this->sex=other.sex;
        cout << "Person的拷贝构造函数" << endl;
    }
    Person &operator=(const Person &other)
    {
        if(&other!=this)
        {
            string name=other.name;
            this->age=other.age;
            this->sex=other.sex;
            cout << "Person的拷贝赋值函数" << endl;
        }
        return *this;
    }
};
class Stu
{
    Person p1;
    double *pd;
public:
    Stu():pd(new double)
    {cout << "Stu的无参构造" << endl;}
    Stu(string name,int age,char sex,double score):p1(name,age,sex),pd(new double(score))
    {cout << "Stu有参构造" << endl;}
    void show()
    {
        p1.show();
        cout << *pd <<endl;
    }
    Stu(const Stu &other):p1(other.p1)
    {
        this->pd=other.pd;
    }
    Stu &operator=(const Stu &other)
    {
        if(&other!=this)
        {
            this->p1=other.p1;
            *(this->pd)=*(other.pd);
            cout << "Stu的拷贝赋值函数" << endl;
        }
        return *this;
    }
};
int main()
{
    Person p2("wangwu",20,'n');
    p2.show();
    Person p3=p2;
    p3.show();
    Person p4;
    p4=p2;
    p4.show();
    Stu s2("zhangsan",20,'n',99.2);
    s2.show();
    Stu s3=s2;
    s3.show();
    Stu s4;
    s4=s2;
    s4.show();
    return 0;
}

#include <iostream>
#include <cstring>
using namespace std;
 
 
using namespace std;
class myString
{
    private:
        char *str;          //变化c风格的字符串
        int size;            //记录字符串的实际长度
    public:
        //无参构造
        myString() : str(new char), size(0)
        {
            str[0] = '\0';
            cout<<"无参构造"<<endl;
        }
        //有参构造
        myString(const char* s)
        {
            size = strlen(s);
            str = new char[size + 1];
            strcpy(str, s);
            cout<<"有参构造"<<endl;
        }
        //拷贝构造
        myString(const myString &other)
        {
            size = other.size;
            str = new char[size + 1];
            strcpy(str, other.str);
            cout<<"拷贝构造函数"<<endl;
        }
        //拷贝赋值函数
        myString& operator=(const myString &other)
        {
             if (this != &other) {
                 
                 size = other.size;
                 str = new char[size + 1];
                 strcpy(str, other.str);
                 cout<<"拷贝赋值函数"<<endl;
             }
             return *this;
         }
        //析构函数
        ~myString()
        {
               delete[] str;
            cout<<"析构"<<endl;
           }
        //判空函数
        void empty()
        {
            if(size == 0)
            {cout<<"空"<<endl;}
            else
            {cout<<"非空"<<endl;}
 
        }
        //size函数
        void mysize()
        {
            cout<<"size = "<<size<<endl;
        }
        //c_str函数
        char* c_str()
        {
            return str;
        }
        //at函数
        char &at(int pos)
        {
            if (pos < 0 || pos >= size) {
                cout<<"位置不合法"<<endl;
            }
            return str[pos];
        }
};
int main()
{
    myString s1("hello");
    myString s2 = s1;
    myString s3;
    cout<<s1.at(4)<<endl;
    cout<<s1.c_str()<<endl;
    cout<<s2.at(4)<<endl;
    cout<<s2.c_str()<<endl;
    s2.empty();
    s2.mysize();
 
    return 0;
}