c++中mystring运算符重载

#include <iostream>
#include <cstring>using namespace std;class mystring
{char* buf;
public:mystring(); //构造函数mystring(const char * str); //构造函数mystring(const mystring& str); //深拷贝函数void show(); //输出函数void setmystr(const mystring& str); //设置函数const char* getmystr() const; //获取函数void append(const mystring& str); //追加函数int isEqual(const mystring& str); // 比较函数void swap(mystring& str);//交换函数~mystring(); //析构函数
/****************************************************************************/mystring& operator+(const mystring& str);//+mystring& operator=(const mystring& str);//=mystring& operator+=(const mystring& str);//+=bool operator==(const mystring& str);//==bool operator!=(const mystring& str);// !=mystring& operator++();//前++mystring operator++(int);//后++char operator[](const int index);//[]friend ostream& operator<<(ostream& out , const mystring& str);//cout << mystringfriend istream& operator>>(istream& in , const mystring& str);//cin >> mystring
};/****************************************************************************/
//+
mystring& mystring::operator+(const mystring& str)
{this->append(str);return *this;
}
//=
mystring& mystring::operator=(const mystring& str)
{int len = strlen(str.buf);buf = new char[len+1];strcpy(buf , str.buf);return *this;
}
//+=
mystring& mystring::operator+=(const mystring& str)
{this->append(str);return *this;
}
//==
bool mystring::operator==(const mystring& str)
{if (strcmp(this->buf , str.buf) == 0 )return true;elsereturn false;
}
// !=
bool mystring::operator!=(const mystring &str)
{if(strcmp(buf , str.buf) == 0)return false;elsereturn true;
}
//++
mystring& mystring::operator++()
{char * p = buf;while (*p != '\0') {++(*p);p++;}return *this;
}
//后++
mystring mystring::operator++(int)
{mystring temp = *this;char * p = buf;while (*p != '\0') {++(*p);p++;}return temp;
}
//[]
char mystring::operator[](const int index)
{int len = strlen(buf);if(index < len){char * p = buf;return *(p+index);}return '\0';
}
//cout << mystring
ostream& operator<<(ostream& out , const mystring& str)
{out << str.buf;return out;
}
//cin >> mystring
istream& operator>>(istream& in , const mystring& str)
{in >> str.buf;return in;
}/****************************************************************************/
//构造函数
mystring::mystring()
{buf = new char[1];
}
//构造函数
mystring::mystring(const char * str)
{int len = strlen(str);buf = new char[len+1];strcpy(buf , str);
}
//深拷贝函数
mystring::mystring(const mystring& str)
{int len = strlen(str.buf);buf = new char[len+1];strcpy(buf , str.buf);
}
//打印函数
void mystring::show()
{cout << buf << endl;
}
//设置函数
void mystring::setmystr(const mystring& str)
{free(this->buf);int len = strlen(str.buf);this->buf = new char[len+1];strcpy(this->buf , str.buf);
}
//获取函数
const char* mystring::getmystr() const
{return buf;
}
//追加函数
void mystring::append(const mystring& str)
{int len1 = strlen(this->buf);char* temp = new char[len1+1];memset(temp , 0 , len1+1);strcpy(temp , this->buf);delete[] buf;int len2 = strlen(str.buf);this->buf = new char[len1+len2+1];memset(buf , 0 , len1+len2+1);strcat(this->buf , temp);strcat(this->buf , str.buf);
}
//比较函数
int mystring::isEqual(const mystring& str)
{if(strcmp(buf , str.buf) > 0){return 1;}else if(strcmp(buf , str.buf) < 0){return -1;}elsereturn 0;
}
//交换函数
void mystring::swap(mystring& str)
{char * temp = this->buf;this->buf = str.buf;str.buf = temp;
}
//析构函数
mystring::~mystring()
{delete[] buf;
}int main()
{mystring ptr;mystring str = "hello world";str.show();ptr.setmystr("hello kitty");cout << ptr.getmystr() << endl;mystring qtr;qtr = ptr + str;qtr.show();/*	ptr += str;ptr.show();  	*//*	if(ptr == str){}else{cout << "== success" << endl;} 				*//*	if(ptr != str){cout << "!= success" << endl;}  				*//*	mystring temp = str++;temp.show();str.show(); 	*///	cout << str[0] <<  str[3] << str[8] << endl;mystring ttr;cout << "请输入：";cin >> ttr;cout << ttr;cout << endl;return 0;
}