4月21日作业

#include <iostream>

#include <cstring>

using namespace std;

//定义类

class myString

{

private:

    char *str;

    int size;

    public:

//无参构造

myString():size(32)

{

    str =  new char[size];

    strcpy(str,"");

    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" << endl;

  }

//析构函数

      ~myString()

      {

          delete []str;

          cout << "析构函数" << endl;

      }

//判空函数

      bool empty()

     {

         if(strlen(str) == 0)

             return true;

         else

             return false;

     }

//size函数

     int mysize()

     {

         return size;

     }

     //c_str函数

     const char *c_str()

     {

         return str;

     }

     //at函数

        char &at(int i)

        {

            if(i >= size || i < 0)

            {

                cout << "段错误" << endl;

            }

            return str[i];

        }

        //展示字符串

        void show()

        {

            cout<<str<<endl;

        }

        //拷贝赋值

        myString & operator=(const myString &R)

        {

            delete []str;

            str=new char[size];

            this->size=R.size;

            this->str=strcpy(this->str,R.str);

            return *this;

        }

        //中括号[]重载

        char operator[](int t)

        {

            return this->str[t];

        }

        //+重载 连接2个字符串

        const myString operator+(const myString &R)

        {

            myString temp;

            delete []temp.str;

            temp.str=new char[this->size+R.size+1];

            temp.str=strcat(this->str,R.str);

            temp.size=this->size+R.size;

            return temp;

        }

        //==重载 判定2个字符串是否相等

        bool operator==(const myString &R)const

        {

            bool a;

            if(0==strcmp(this->str,R.str))

                a=1;

            else

                a=0;

            return a;

        }

         //<重载

        bool operator<(const myString &R)const

        {

            bool a;

            if(0<strcmp(this->str,R.str))

                a=1;

            else

                a=0;

            return a;

        }

        //>重载

       bool operator>(const myString &R)const

       {

           bool a;

           if(0>strcmp(this->str,R.str))

               a=1;

           else

               a=0;

           return a;

       }

       friend ostream &operator<<(ostream &L,const myString &O);

       friend istream &operator>>(istream &L, myString &O);

};

//输出重载<<

ostream &operator<<(ostream &L,const myString &O)

{

    L<<O.str;

    return L;

}

//输入重载>>

istream &operator>>(istream &L, myString &O)

{

    L>>O.str;

    return L;

}

int main()

    {

        myString s1;//无参构造

        myString s2("hello");//有参构造

        myString s3(s2);//拷贝构造

        cout<<"s3=";

        s3.show();

        int a=s2.mysize();//计算长度

        cout<<"s2长度="<<a<<endl;

        myString s4("aaa");

        myString s5;

        s5=s4;//赋值

        cout<<"s5="<<s5<<endl;//打印s5字符串

        cout<<"s5[2]="<<s5[2]<<endl;

        myString s6;

        s6=s4+s5;//连接字符串

        cout<<"s6="<<s6<<endl;

        myString s7;

        cin>>s7;

        if(s7<s6)

            cout<<"s7<s6";

        else if(s7>s6)

            cout<<"s7>s6";

        else if(s7==s6)

            cout<<"s7=s6";

    }