String class

[firix]

class String{
	struct Srep{
		char *s;
	int sz;
	int n;
	Srep(int nsz, const char *p)
	{
		n = 1;
		sz = nsz;
		s = new char[sz + 1];
		strcpy(s, p);
	}

	~Srep()
	{
		delete[]s;
	}

	Srep *get_own_copy()
	{
		if (n == 1)
			return this;
		n--;
		return new Srep(sz, s);
	}

	void assign(int nsz, const char *p)
	{
		if (sz != nsz){
			delete []s;
			sz = nsz;
			s = new char[sz+1];
		}

		strcpy(s, p);
	}


private:
	Srep(const Srep &s);
	Srep &operator=(const Srep &s);

	};

	Srep *rep;
public:
	class Cref{        // reference to char
		friend class String;
		String &s;
		int i;
		Cref(String &ss, int ii):s(ss), i(ii){}
	public:
		operator char() { return s.Read(i);}
		void  operator=(char c){s.write(i, c);}
	};
	class Range{
		char *s;
	public:
		Range(char *ss):s(ss){}
	};
	String()
	{
		rep = new Srep(0, " ");
	}
	String(const char *s)
	{	

		rep = new Srep(strlen(s), s);
	}
	String(const String &s)
	{
		s.rep->n++;
		rep = s.rep;   // Share representation 
	}
	String &operator=(const char *s)
	{
		if (rep->n == 1)
			rep->assign(strlen(s), s);
		else {
			rep->n--;
			rep = new Srep(strlen(s), s);
		};

		return *this;
	}
	String &operator=(const String &s)
	{
		s.rep->n++;
		if(--rep->n == 0)
			delete rep;
		rep = s.rep;
		return *this;
	}
	~String()
	{
		if (--rep->n == 0)
			delete rep;

	}

	void check(int i)const
	{
		if (i < 0 || rep->sz <= i)
			throw Range("entered value is error");
	}
	char Read(int i)const
	{
		return rep->s[i];
	}
	void write(int i, char c)
	{
		rep  = rep->get_own_copy(), rep->s[i] = c;

	}
	Cref operator[](int i)
	{
		check(i);
		return Cref(*this, i);
	}
	char operator[](int i)const
	{
		check(i);
		return rep->s[i];
	}


	operator char*()const
	{
		return rep->s;
	}

    operator const char*()const
	{
		return rep->s;
	}



	String &operator+=(const String &s1)
	{
		*this->rep->s += *s1.rep->s;
		return *this;
	}

	String &operator +=(const char *s1)
	{
		*this->rep->s += *s1;
		return *this;

	}


	friend ostream& operator<<(ostream &os, const String &s);
	friend istream& operator>>(istream &is, String &s);
	friend bool operator==(const String &s, const char  *cs);
	friend bool operator==(const String &s1, const String &s2);
	friend bool operator!=(const String &s, const char  *cs);
	friend bool operator!=(const String &s1, const String &s2);
	friend bool operator>=(const String &s1, const String &s2);
	friend bool operator<=(const String &s1, const String &s2);
	friend bool operator>(const String &s1, const String &s2);
	friend bool operator<(const String &s1, const String &s2);




};


	ostream& operator<<(ostream &os, const String &s)
	{
		return os << "(" << s.rep->s << ")";
	}

	istream& operator>>(istream &is, String &s)
	{
		return is >> s.rep->s;
	}

	bool operator==(const String &s, const char  *cs)
	{
		return strcmp(s.rep->s, cs) == 0;
	}

	bool operator==(const String &s1, const String &s2)
	{
		return strcmp(s1.rep->s, s2.rep->s) == 0;
	}

	bool operator!=(const String &s, const char  *cs)
	{
		return strcmp(s.rep->s, cs) != 0;
	}

	bool operator!=(const String &s1, const String &s2)
	{
		return strcmp(s1.rep->s, s2.rep->s) != 0;
	}

	bool operator>=(const String &s1, const String &s2)
	{
		if (strcmp(s1.rep->s, s2.rep->s) >= 0)
			return true;
		else
			return false;	
	}

	bool operator<=(const String &s1, const String &s2)
	{
		if (strcmp(s1.rep->s, s2.rep->s) <= 0)
			return true;
		else
			return false;	
	}


	bool operator<(const String &s1, const String &s2)
	{
		if (strcmp(s1.rep->s, s2.rep->s) < 0)
			return true;
		else
			return false;	
	}

	bool operator>(const String &s1, const String &s2)
	{
		if (strcmp(s1.rep->s, s2.rep->s) > 0)
			return true;
		else
			return false;	
	}

int main()
{
	
	String s1 =	"Firix";

	String s2("BILL");

	String s3;      // error


	s1 += s3;       // error

	s1 += "BILL";   // error


	cout << s1 << endl;
	cout << s2 << endl;
	cout << s3 << endl;


	return 0;
}

Hi;

Can not create a specific object class in every way.
Pointed out errors in the above areas.
I'll be very happy if you help.

[Disch]

it might help if you told us what the errors were.

[firix]

where the error was already pointed out above.

error the following:

can not create object in the following way:

String s;

I can not like this assignment:

s1 += s3;  

s1 += "BILL";

How do I solve these problems