#include <iostream>
//#include <cstring>//包含char*的字符串处理函数
using namespace std;class String
{
public:String(){p=NULL;}String(char *str);void diaplay();friend bool operator>(String &str1,String &str2);//重载>操作符friend ostream & operator <<(ostream&,String &str);friend istream & operator >>(istream&,String &str);
private:char *p;
};
String::String(char *str)
{p=str;
}
void String::diaplay()
{cout<<p;
}
bool operator>(String &str1,String &str2)
{if (strcmp(str1.p,str2.p)>0){return true;}else return false;
}
ostream& operator <<(ostream& output,String &str)
{output<<str.p;return output;
}
istream& operator >>(istream& input,String &str)
{//input>>str.p;//没有分配空间，无法读入。str.p=new char[256];input>>str.p;return input;//
//     char q[256];
//     input>>q;
//     //p.length =strlen(q);
//     str.p=new char[strlen(q)+1];
//     strcpy(str.p,q);
//     return input;

}
int main()
{String str1("Hello,pig!"),str2;cin>>str2;str1.diaplay();bool b=str1>str2;cout<<'\n'<<b<<endl;cout<<str2<<endl;
}

#include <iostream>
//#include <cstring>//包含char*的字符串处理函数
using namespace std;class String
{
public:String(){p=NULL;len=0;}String(int);String(char *str);String (String&);~String(){delete[] p;}void Clear();//清空本串int mystrlen();bool IsEmpty();//判断本串是否为空String Substr(int index,int count);//从index开始提取count个字符的字串int Find(char c,int start);//从下标start开始找到c后，返回字符c 在本串的下标char & operator [](int i);//重载[]操作符operator char *();//将String类对象转换为普通字符串
friend bool operator>(String &str1,String &str2);//重载>操作符friend ostream & operator <<(ostream&,String &str);friend istream & operator >>(istream&,String &str);
private:char *p;//字符串指针int len;//字符串长度,不包含最后的\0
};String::String(int length)
{len=length;p=new char[length+1];
}
String::String(char *str)
{if (str==NULL){len=0;p=NULL;}else{len=strlen(str);p=new char[len+1];strcpy(p,str);//深拷贝
    }//p=str;//只写这个是浅拷贝，只拷贝了指针
}
String::String(String &other)
{len=other.len;p=new char[len+1];strcpy(p,other.p);
}
bool String::IsEmpty()
{return (!this->len);
}void String::Clear()
{if (!IsEmpty()){delete[]p;len=0;}
}
int String::mystrlen()
{return len;
}
int String::Find(char c,int start)
{int i;if (start>len) cout<<"超出范围"<<endl;//return NULL;else{for (i =start;i<len;++i){if (p[i]==c) break;}return i;}
}
String String::Substr(int index,int count)
{if (index+count>len) cout<<"超出范围"<<endl;else{String str(count);str.len=count;for (int i=0;i<count;i++,index++)str.p[i]=p[index];str.p[count]='\0';return str;}}
char & String::operator[](int i)
{if (i<0||i>len-1){cout<<"越界"<<endl;}else{return p[i];}
}
//类型转换
String::operator char *()
{return (char *)p;
}bool operator>(String &str1,String &str2)
{if (strcmp(str1.p,str2.p)>0){return true;}else return false;
}
ostream& operator <<(ostream& output,String &str)
{output<<str.p;return output;
}
istream& operator >>(istream& input,String &str)
{//input>>str.p;//没有分配空间，无法读入。str.p=new char[256];input>>str.p;return input;////或者：
//     char q[256];
//     input>>q;
//     str.p=new char[strlen(q)+1];
//     strcpy(str.p,q);
//     return input;

}
int main()
{String str3("hello");  int pos;  cout<<"\n测试Find功能"<<endl;  pos = str3.Find('e',0);  cout<<str3<<endl;  cout<<pos<<endl;  cout<<"\n测试Substr功能"<<endl;  cout<<str3.Substr(1,2)<<endl;  cout<<"\n测试重载<< >>功能"<<endl;  String c;  cout<<"请输入一段字符串"<<endl;  cin>>c;  cout<<c<<endl;  cout<<"测试字符串C函数的应用"<<endl;  String f(40);  char *e = " this is a test";  char g[50]="hahahhah";strcpy(f,e); //隐含执行了默认类型转换(char *)f; cout<<f<<endl;  strcat(g,f);  cout<<g<<endl; cout<<"\n测试IsEmpty _strlen功能"<<endl;  String d("tihs is a test");  if(d.IsEmpty())  cout<<"d 是空字符串"<<endl;  else  cout<<"d 非空字符串 \t长度:"<<d.mystrlen()<<endl;  return 0;  }