类的应用

#include <iostream>
#include<stdlib.h>
#include<string.h>
using namespace std;

class StringClass
{
	char* s;
	int n;
	friend istream& operator>>(istream& istr, StringClass& r);
	friend ostream& operator<<(ostream& ostr, StringClass& r);
public:
	StringClass() { s = new char('\0'); n = 0; }
	StringClass(char* r);
	StringClass(StringClass& t);
	StringClass& operator=(char *r);
	StringClass& operator=(StringClass& t);
	bool operator==(char* r);
	bool operator==(StringClass& t);
	bool operator<(char* r);
	bool operator>(StringClass& t);
	StringClass operator+(char* r);
	StringClass operator+(StringClass& t);
	char& operator[](int i);
	int Strlen() const { return n; }
	~StringClass()   { delete[]s; }
};

StringClass::StringClass(char* r)
{
	n = strlen(r);
	s = new char[n + 1];
	strcpy(s, r);
}

StringClass::StringClass(StringClass& t)
{
	n = t.n;
	s = new char[n + 1];
	strcpy(s, t.s);
}

StringClass& StringClass::operator=(char* r)
{
	delete[]s;
	n = strlen(r);
	s = new char[n + 1];
	strcpy(s, r);
	return *this;
}

StringClass& StringClass::operator=(StringClass& t)
{
	delete[]s;
	n = t.n;
	s = new char[n + 1];
	strcpy(s, t.s);
	return *this;
}

bool StringClass::operator==(char* r)
{
	if (s == NULL && r == NULL)return true;
	else if (s == NULL || r == NULL)return false;
	int i = 0;
	while (s[i] != NULL&&r[i] != NULL)
		if (s[i] != r[i]) return false;
		else i++;
		if (s[i] == NULL&&r[i] == NULL) return true;
		else return false;
}

bool StringClass::operator==(StringClass& t)
{
	if (s == NULL&&t.s == NULL) return true;
	else if (s == NULL || t.s == NULL) return false;
	int i = 0;
	while (s[i] != NULL&&t.s[i] != NULL)
		if (s[i] != t.s[i]) return false;
		else i++;
	if (s[i] == NULL&&t.s[i] == NULL) return true;
	else return false;
}