C++ 重载解引用_迭代器

1 C++ 重载解引用_迭代器.cpp

#include<iostream>
#include<string.h>
using namespace std;
//实现迭代器的目的是可以进行泛型计算，比如使用范围for语句等等;
//实现迭代器的步骤：
//1,定义一个内部类iterator
//2,重载该内部类的!=, ++, *
//3,定义外部类的begin和end成员方法

class my_string{
    private:
    char* p=nullptr;
    public:
    class iterator{
        int pos=0;
        char * ip=nullptr;
        public:
        iterator(){};
        iterator(char *i,int p)
        :ip(i),pos(p){}
#if 0
        iterator(iterator & i){
            pos = i.pos;
            ip = i.ip;
        }
#endif
        ~iterator(){}
        bool operator!=(iterator it)
        {
            return this->pos != it.pos;
        }
        iterator operator++()
        {
            pos++;
            return *this;
        }
        char & operator*()
        {
            return ip[pos];
        }
    };
    iterator begin()
    {
        return iterator(p,0);
    }
    iterator end()
    {
        return iterator(p,strlen(p));
    }
    my_string(){}
    my_string(const char* s){
        if(s){
            p = new char[strlen(s)+1];
            strcpy(p,s);
        }
    }
    my_string( const my_string& ms){
        if(ms.p){
            if(p)delete []p;
            p = new char[ms.size()+1];
            strcpy(p,ms.p);
        }
    }
    ~my_string(){
        if(p)delete [] p;
    }
friend ostream &operator<<(ostream&cout,my_string &s);
    char & operator[](int pos)
    {
        return p[pos];
    }
    int size()const{return strlen(p);}
    my_string operator+(my_string s)
    {
        my_string tmp;
        tmp.p= new char[this->size()+s.size()+1];
        strcpy(tmp.p,this->p);
        strcat(tmp.p,s.p);
        return tmp;
    }
    my_string operator+(const char* s)
    {
        my_string tmp;
        tmp.p= new char[this->size()+strlen(s)+1];
        strcpy(tmp.p,this->p);
        strcat(tmp.p,s);
        return tmp;
    }
    //如果返回值和参数都是对象而不是引用，那么一定记得要先定义拷贝构造函数，而且该拷贝构造内部完成的是深拷贝
    my_string operator=(my_string s)
    {
        if(this->p)delete[]p;
        if(s.p){
            p=new char[s.size()+1];
            strcpy(this->p,s.p);
        }else{
            this->p = nullptr;
        }
        return *this;
    }
};

ostream &operator<<(ostream&cout,my_string &s)
{
    cout<<s.p;
    return cout;
}

int main()
{
#if 0
    string s="123";
    string::iterator it;
//  std::basic_string<char>::iterator it;

//  for(auto k:s)
//  char k;
    for(it=s.begin();it != s.end();++it)    
        cout<<*it;
    cout<<endl;
#else
    my_string ms="123";
//  my_string::iterator it;
//  for(it=ms.begin();it != ms.end();++it)  
//      cout<<*it;
    for(auto k:ms)
        cout<<k;
    cout<<endl;
#endif
    return 0;
}