1、 将昨天的My_string类中的所有能重载的运算符全部进行重载

+、[] 、>、=、>)

头文件

#ifndef MY_STRING_H
#define MY_STRING_H#endif // MY_STRING_H#include <iostream>
#include <cstring>
//#include <stdexcept>using namespace std;class My_string
{
private:char *ptr;         //指向字符数组的指针int size;           //字符串的最大容量int len;            //字符串当前容量public://加法const My_string operator+(const My_string &R)const;const My_string operator+=(const My_string &R);char operator[](int index)const;friend ostream & operator<< (ostream &L,const My_string &R);friend istream & operator>> (istream &L,My_string &R);bool  operator>(My_string &R);bool  operator<(My_string &R);bool  operator==(My_string &R);bool  operator<=(My_string &R);bool  operator>=(My_string &R);bool  operator!=(My_string &R);//无参构造My_string();//有参构造My_string(const char* src);My_string(int num, char value);//拷贝构造My_string(const My_string &other);//拷贝赋值My_string& operator= (const My_string &other);//析构函数~My_string();//判空bool  empty();//尾插void push_back(char value);//尾删void pop_back();//at函数实现char &at(int index);//清空函数void clear();//返回C风格字符串char *data();//返回实际长度int get_length();//返回当前最大容量int get_size();
};

源文件

#include "My_string.h"
//加法
const My_string My_string::operator+(const My_string &R)const
{My_string result;result.len = len + R.len;result.size = size + R.size;result.ptr = new char[result.size];strcpy(result.ptr,ptr);strcat(result.ptr,R.ptr);return result;}
//加等
const My_string My_string::operator+=(const My_string &R)
{*this = *this + R;return *this;
}char My_string::operator[](int index)const
{if(index<0 || index>len){return -1;}return ptr[index];
}ostream & operator<< (ostream &L,const My_string &R)
{L<<R.ptr<<endl;return L;
}istream & operator>> (istream &L,My_string &R)
{char buff[1024];L >> buff;R.len = strlen(buff);R.size = R.len + 1;delete [] R.ptr;R.ptr = new char[R.size];strcpy(R.ptr,buff);return L;
}bool My_string:: operator>(My_string &R)
{return strcmp(ptr,R.ptr)>0;
}bool My_string:: operator<(My_string &R)
{return strcmp(ptr,R.ptr)<0;
}bool My_string:: operator==(My_string &R)
{return strcmp(ptr,R.ptr)==0;
}bool My_string:: operator<=(My_string &R)
{return strcmp(ptr,R.ptr)<=0;
}bool My_string:: operator>=(My_string &R)
{return strcmp(ptr,R.ptr)>=0;
}bool My_string:: operator!=(My_string &R)
{return strcmp(ptr,R.ptr)!=0;
}//无参构造
My_string::My_string():size(15)
{this->ptr = new char[size];this->ptr[0] = '\0';            //表示串为空串this->len = 0;
}//有参构造
My_string:: My_string(const char* src)
{len = strlen(src);size = len+1;ptr = new char[size];strcpy(ptr,src);
}
My_string:: My_string(int num, char value): size(num+1),len(num)
{ptr = new char[size];for(int i=0;i<num;i++){ptr[i] = value;}ptr[num] = '\0';
}
//拷贝构造
My_string:: My_string(const My_string &other):size(other.size),len(other.len)
{ptr = new char[size];strcpy(ptr,other.ptr);
}
//拷贝赋值
My_string & My_string ::operator =(const My_string &other)
{if(this ==&other){return *this;}delete [] ptr;size = other.size;len = other.len;ptr = new char[size];strcpy(ptr,other.ptr);return *this;
}
//析构函数
My_string:: ~My_string()
{delete [] ptr;
}
//判空
bool My_string:: empty()
{return len ==0;
}
//尾插
void My_string:: push_back(char value)
{if(len+1>=size){size *=2;char* new_ptr = new char[size];strcpy(new_ptr,ptr);delete []ptr;ptr = new_ptr;}ptr[len] = value;len++;ptr[len] = '\0';
}
//尾删
void My_string:: pop_back()
{if(len>0){len--;ptr[len]='\0';}
}
//at函数实现
char&My_string:: at(int index)
{if(index<0 ||index>=len){//throw  out_of_range("超出");}return ptr[index];
}
//清空函数
void My_string:: clear()
{len = 0;ptr[0] = '\0';
}
//返回C风格字符串
char*My_string:: data()
{return ptr;
}
//返回实际长度
int My_string:: get_length()
{return len;
}
//返回当前最大容量
int My_string:: get_size()
{return size;
}

2、 思维导图