2022.08.24运算符重载

代码实现

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

using namespace std;
class my_string
{
private:
    char *str;
    int len;
public:

    //无参构造
    my_string(){}
    //有参构造
    my_string(char *q,int i)
    {
        str=new char[128];
        strcpy(str,q);
        len = i;
        cout<<"this is a has parament constroctor"<<endl;
    }
    //拷贝构造
    my_string(const my_string &O)
    {
        str=new char[128];
        this->len = O.len;
        strcpy(str,O.str);
    }
    //拷贝赋值
    my_string& operator=(const my_string &O)
    {
        if(this!=&O)
        {
            len = O.len;
            str = new char[128];
            strcpy(str,O.str);
        }
        return *this;
    }
    //bool my_empty()        判空
    bool my_empty()
    {
        if(my_size()==0)
            return true;
        else
        {
            cout<<str;
            return false;
        }
    }
    //int my_size()          求长度
    int my_size()
    {
        int i=0;
        while(*(str+i)!=0)
        {
            i++;
        }
        return i;
    }
    //转化为c风格字符串
    char *my_str()
    {
        return str;
    }
    //关系运算符<
        bool operator <(const my_string &R){
            char *p=this->str;
            char *q=R.str;
            int n;

            while(*p && *q && *p==*q){
                p++;
                q++;
            }
            n=*p-*q;
            if(n<0)return true;
            else return false;
        }

        //关系运算符>=
        bool operator >=(const my_string &R){
            char *p=this->str;
            char *q=R.str;
            int n;

            while(*p && *q && *p==*q){
                p++;
                q++;
            }
            n=*p-*q;
            if(n>=0)return true;
            else return false;
        }
        //关系运算符<=
        bool operator <=(const my_string &R){
            char *p=this->str;
            char *q=R.str;
            int n;

            while(*p && *q && *p==*q){
                p++;
                q++;
            }
            n=*p-*q;
            if(n<=0)return true;
            else return false;
        }
        //关系运算符==
        bool operator ==(const my_string &R){
            char *p=this->str;
            char *q=R.str;
            int n;

            while(*p && *q && *p==*q){
                p++;
                q++;
            }
            n=*p-*q;
            if(n==0)return true;
            else return false;
        }
        //关系运算符!=
        bool operator !=(const my_string &R){
            char *p=this->str;
            char *q=R.str;
            int n;

            while(*p && *q && *p==*q){
                p++;
                q++;
            }
            n=*p-*q;
            if(n!=0)return true;
            else return false;
        }
        //+运算符
        my_string operator +(const my_string &R)const{
            my_string temp;
            strcat(temp.str,this->str);
            strcat(temp.str,R.str);
            temp.len=this->len+R.len;
            return temp;
        }
        //取成员运算符
        char operator [](const int n){
            return this->str[n-1];
        }


};
int main()
{
    //验证有参构造
       my_string str1("Hello World!",10);
       cout<<"str1:"<<str1.my_str()<<endl;
       my_string str2("h",10);
       cout<<"str2:"<<str2.my_str()<<endl;

       //验证拷贝构造
       my_string str3=str1;
       cout<<"str3"<<str3.my_str()<<endl;

       //验证赋值构造
       my_string str4;

       //验证判空
       my_string str5("",0);
       if(str5.my_empty())
           cout<<" no str5"<<endl;
       else
           cout<<"have str5"<<endl;

       if(str4.my_empty())
           cout<<"no str4"<<endl;
       else
           cout<<"have str4"<<endl;
       //获取长度
       int len=str1.my_size();
       cout<<"the lenth of str1:"<<len<<endl;

    cout << "Hello World!" << endl;
    return 0;
}

运行结果