创建一个简单的string类

#include <iostream>using namespace std;class String{public:String();//默认构造函数String(const char*const ch);//带参数的构造函数String(unsigned short int length);String(const String&rs); //利用复制构造函数赋值~String();char&operator[](unsigned short int length); //限制数组越界char operator[](unsigned short int length)const;String&operator==(const String&s);String operator+(const String&rs); void operator+=(const String&rs);friend ostream &operator<<(ostream &o,const String &str){o<<str.str;return o;}friend istream &operator>>(istream &i,String &str){i>>str.str;return i;}friend bool operator<(const String&str1,const String&str2){if(strcmp(str1.str,str2.str)<0)return 1;else return 0;}friend bool operator>(const String&str1,const String&str2){if(strcmp(str1.str,str2.str)>0)return 1;else return 0;}friend bool operator==(const String&str1,const String&str2){if(strcmp(str1.str,str2.str)==0)return 1;else return 0;}int getlen()const{return len;}const char*getstr()const{return str;}private:int len;char*str;};String::String() //默认构造函数{len=0;str=new char[1];str[0]='/0';}String::String(const char*const ch){len=strlen(ch);str=new char[len+1];for(int i=0;i<len;i++)str[i]=ch[i];str[len]='/0';}char&String::operator[](unsigned short int length){ if(length>len){return str[len-1];}else return str[length];}String::String(const String&rs){len=rs.getlen();str=new char[len+1];for(int i=0;i<len;i++){str[i]=rs[i];}str[len]='/0';}char String::operator[](unsigned short int length)const{if(length>len){return str[len-1];}elsereturn str[length];}String&String::operator==(const String&s){if(this==&s)return *this;delete []str;len=s.getlen();str=new char[len+1];for(int i=0;i<len;i++)str[i]=s[i];str[len]='/0';return *this;}String String::operator+(const String&rs){int total=len+rs.getlen();String temp(total);int j,i;for(i=0;i<len;i++)temp[i]=str[i];for(j=0;j<rs.getlen();j++,i++)temp[i]=rs[j];temp[total]='/0';return temp;}String::String(unsigned short int length){len=length;str=new char[length+1];int i;for(i=0;i<=length;i++)str[i]='/0';}String::~String(){ delete []str;len=0;}void String::operator+=(const String&rs){int total=len+rs.getlen();String temp(total); int i,j;for(i=0;i<len;i++)temp[i]=str[i];for(j=0;j<rs.getlen();j++,i++)temp[i]=rs[j];temp[total]='/0';*this=temp;}int main(){String s1="aaa";String s2="bbb";cout<<s1+s2;return 0;}