C++(day4)

思维导图

封装Mystring

#include <iostream>
#include<cstring>using namespace std;class Mystring{
public://无参构造函数Mystring():size(10){str=new char[size];strcpy(str,"");cout<<"无参构造函数"<<endl;}//有参构造函数Mystring(const char *s){size=strlen(s);str=new char[size+1];strcpy(str,s);cout<<"有参构造函数"<<endl;}//拷贝构造函数Mystring(const Mystring &other){this->size=other.size;this->str=new char[this->size];strcpy(this->str,other.str);cout<<"拷贝构造函数"<<endl;}//析构函数~Mystring(){delete []str;cout<<"析构函数"<<endl;}//拷贝赋值函数Mystring &operator=(const Mystring &other){if(this!=&other){this->size=other.size;strcpy(this->str,other.str);}cout<<"拷贝赋值函数"<<endl;return *this;}//判空函数bool empty()const{return !strlen(this->str);}//size函数int strsize()const{return strlen(this->str);}//c_str函数char *c_str(){return this->str;}//at函数char &at(int pos){return *(this->str+pos-1);}//加号运算符重载Mystring operator+(const Mystring &R)const{Mystring temp;strcat(temp.str,this->str);strcat(temp.str,R.str);return temp;}//加等于运算符重载Mystring &operator+=(const Mystring &R){strcat(this->str,R.str);return *this;}//关系运算符重载（>）bool operator>(const Mystring &R)const{if(strcmp(this->str,R.str)>0){return true;}else{return false;}}//中括号运算符重载char &operator[](int pos)const{return *(this->str+pos-1);}//展示函数void show(){cout<<str<<endl;}
private:char *str;  //字符串首地址int size;   //字符串大小
};int main()
{Mystring str1("hello");str1.show();Mystring str2("world");str2.show();Mystring str3;if(str3.empty()){cout<<"str3现在为空,字符串长度为"<<str3.strsize()<<endl;}str3=str1;str3.show();if(!str3.empty()){cout<<"str3现在不为空,字符串长度为"<<str3.strsize()<<endl;}Mystring str4=str2;str4.show();str4+=str3;str4.show();cout<<"str4字符串第7位是"<<str4.at(7)<<",str4字符串第13位是"<<str4[13]<<endl;cout<<str4.c_str()<<endl;if(str3>str2){cout<<"str3>str2"<<endl;}else{cout<<"str3<str2"<<endl;}return 0;
}