自己定义mystring类实现string功能

#include <iostream>
#include<cstring>
using namespace std;

class myString
{
    private:
        char *str;          //记录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():size(10)
        {
            str = new char[size];         //构造出一个长度为10的字符串
            strcpy(str,"");
        }
        //有参构造
        myString(const char *s)
        {
            size = strlen(s);
             str = new char[size+1];
             strcpy(str, s);
        }

        //拷贝构造
        myString(myString &m)
        {
            size=strlen(m.str);
            str=new char[size+1];
            strcpy(str,m.str);
            cout<<"拷贝构造函数"<<endl;
        }
        //析构函数
        ~myString()
        {
            delete [] str;
            cout<<"析构函数"<<endl;
        }
        //判空函数
        int myempty()
        {
            if(!strcmp(str,""))
                return 0;
            return true;
        }

        //size函数
        int mysize()
        {
            return strlen(str);
        }
        //c_str函数
        char* &myc_str()
        {
            return str;
        }
        //at函数
        char &at(int pos)
        {
            int l=strlen(str);
            if(pos>l)
            {
                cout<<"pos超出范围"<<endl;

            }
            return str[pos];
        }

};
int main()
{
    myString s1("1234");
    cout<<"s1= "<<s1.myc_str()<<endl;
    myString s2=s1;
    cout<<"s2= "<<s2.myc_str()<<endl;
    cout<<"length= "<<s2.mysize()<<endl;
    if(!s2.myempty())
        cout<<"字符串为空"<<endl;
    else
        cout<<"字符串不为空"<<endl;
    cout<<"s2[1]="<<s2.at(1)<<endl;

}