class String
{ //友原重载<<和>>
  friend ostream& operator<<(ostream& out, const String& s);
  friend istream& operator>>(istream& in, String& s);
public:
  String() {
    str = new char[100];
    str[0] = '\0';
  }//string的默认构造
  String(const char* other)
  {
    str = new char[strlen(other) + 1];
    strcpy(str, other);
  }//有参构造
  ~String()
  {
    delete[]str;
  }//析构
  String(const String& other);//复制构造
  int Length();//字符串的长度
  String& operator=(const String& other);
  String& operator=(const char* ch);//重载=
  String operator+(const String& other);//重载+
  String& operator+=(const String& other);//重载+=
  char& operator[](int x);//重载[]
  bool operator==(const String& other);//重载==
  bool operator<(const String& other);//重载<
private:
  char* str;
};

ostream& operator<<(ostream& out, const String& s)
{
  out << s.str;
  return out;
}
istream& operator>>(istream& in, String& s)
{
  char ch[1000];//临时创造一个数组储存输入值
  in >> ch;
  delete[]s.str;//释放s的空间
  s.str = new char[strlen(ch) + 1];//为s重新分配新的空间
  strcpy(s.str, ch);//赋值给s
  return in;
}

String::String(const String& other)
{
  str = new char[strlen(other.str) + 1];
  strcpy(str, other.str);
}

int String::Length()
{
  return strlen(str);//返回str的长度
}

String& operator=(const String& other)
  {
    if (this != &other)//判断是否和原来一样，一样直接返回原值
    {
      delete[]str;
      str = new char[strlen(other.str) + 1];
      strcpy(str, other.str);
    }
    return *this;
  }//重载与string的=
  String& operator=(const char* ch)
  {
    delete[]str;
    str = new char[strlen(ch) + 1];
    strcpy(str, ch);
    return *this;
  }//重载与字符串的=

String operator+(const String& other)
  {
    int len = strlen(str) + strlen(other.str) + 1;
    //求出需要开辟空间的大小
    char* newstr = new char[len];//用一个新指针去接收
    strcpy(newstr, str);
    strcat(newstr, other.str);
    return String(newstr);
  }//重载+

String& operator+=(const String& other)
  {
    *this = *this + other;
    return *this;
  }//使用重载后的=和+完成+=的重载

  char& operator[](int x)
  {
    assert(x >= 0 && x <= strlen(str));
    //使用断言判断是否在范围内
    return str[x];
  }//重载[]
  bool operator==(const String& other)
  {
    return !strcmp(str, other.str);
  }//重载==
  bool operator<(const String& other)
  {
    return strcmp(str, other.str) < 0;
  }//重载<

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <string>
#include <cassert>
using namespace std;
class String
{ //友原重载<<和>>
  friend ostream& operator<<(ostream& out, const String& s);
  friend istream& operator>>(istream& in, String& s);
public:
  String() {
    str = new char[100];
    str[0] = '\0';
  }//string的默认构造
  String(const char* other)
  {
    str = new char[strlen(other) + 1];
    strcpy(str, other);
  }//有参构造
  ~String()
  {
    delete[]str;
  }//析构
  String(const String& other);//复制构造
  int Length();//字符串的长度
  String& operator=(const String& other)
  {
    if (this != &other)
    {
      delete[]str;
      str = new char[strlen(other.str) + 1];
      strcpy(str, other.str);
    }
    return *this;
  }//重载与string的=
  String& operator=(const char* ch)
  {
    delete[]str;
    str = new char[strlen(ch) + 1];
    strcpy(str, ch);
    return *this;
  }//重载与字符串的=
  String operator+(const String& other)
  {
    int len = strlen(str) + strlen(other.str) + 1;
    char* newstr = new char[len];
    strcpy(newstr, str);
    strcat(newstr, other.str);
    return String(newstr);
  }//重载+
  String& operator+=(const String& other)
  {
    *this = *this + other;
    return *this;
  }//使用重载后的=和+完成+=的重载
  char& operator[](int x)
  {
    assert(x >= 0 && x <= strlen(str));
    return str[x];
  }//重载[]
  bool operator==(const String& other)
  {
    return !strcmp(str, other.str);
  }//重载==
  bool operator<(const String& other)
  {
    return strcmp(str, other.str) < 0;
  }//重载<
private:
  char* str;
};
String::String(const String& other)
{
  str = new char[strlen(other.str) + 1];
  strcpy(str, other.str);
}
ostream& operator<<(ostream& out, const String& s)
{
  out << s.str;
  return out;
}
istream& operator>>(istream& in, String& s)
{
  char ch[1000];
  in >> ch;
  delete[]s.str;
  s.str = new char[strlen(ch) + 1];
  strcpy(s.str, ch);
  return in;
}
int String::Length()
{
  return strlen(str);
}
int main()
{
  String s1("Help!"), s2("Good!"), s3(s2), s4, s5;
  cout << "s1=" << s1 << endl;
  s3 = "Hello!";
  cout << "s3=" << s3 << endl;
  s3 = s2;
  cout << "s3=" << s3 << endl;
  s3 += s2;
  cout << "s3=" << s3 << endl;
  cin >> s4;
  cout << "s4=" << s4 << endl;
  s5 = s3 + s4;
  cout << "s5=" << s5 << endl;
  s5[0] = 'g';
  cout << "s5=" << s5 << endl;
  cout << "strlen(s5)=" << s5.Length() << endl;
  cout << boolalpha << (s3 == s1) << endl;
  //利用boolalpha来断真假
  cout << boolalpha << (s3 < s1) << endl;
}