BiteString

#include <iostream>
class String
{
protected:
	char* str;
public:
	String(const char* str_)
	{
		str = new char[strlen(str_) + 1];
		strcpy_s(str, strlen(str_) + 1, str_);
	}
	String(const String& copy)
	{
		str = new char[strlen(copy.str) + 1];
		strcpy_s(str, strlen(copy.str) + 1, copy.str);
	}
	String() : String(" ") {};
	~String()
	{
		delete[] str;
	}
	void operator +=(String& rhs)
	{
		*this = *this + rhs;
	}
	int getSize()
	{
		return strlen(str);
	}
	void clear()
	{
		delete[] str;
		str = new char[1]{""};
	}
	virtual char* plus( String& rhs)
	{
		char* copy = new char[strlen(str) + strlen(rhs.str) + 1];
		int num = strlen(str) + 1;
		for (int i = 0; i <= num; ++i)
		{
			copy[i] = str[i];
		}
		num = strlen(rhs.str) + 1;
		for (int i = strlen(str), d = 0; d < num; ++i, ++d)
		{
			copy[i] = rhs.str[d];
		}
		return copy;
	}
	virtual void operator = (const String& copy);
	friend const String operator +(String& lhs, String& rhs);
	friend std::ostream& operator<<(std::ostream& out, String& str);
	friend std::istream& operator>>(std::istream& in, String& str);
	friend bool operator == (const String& lhs, const String& rhs);
	friend bool operator != (const String& lhs, const String& rhs);
};
void String :: operator = (const String& copy)
{
	if (strlen(str) >= strlen(copy.str))
	{
		strcpy_s(str, strlen(copy.str) + 1, copy.str);
	}
	else
	{
		delete[] str;
		str = new char[strlen(copy.str) + 1];
		strcpy_s(str, strlen(copy.str) + 1, copy.str);
	}
}
bool operator ==(const String& lhs, const String& rhs)
{
	return !(strcmp(lhs.str, rhs.str));
}
bool operator !=(const String& lhs, const String& rhs)
{
	return (strcmp(lhs.str, rhs.str));
}
const String operator +( String& lhs, String& rhs)
{
	return String(lhs.plus(rhs));
}
std::istream& operator>>(std::istream& in, String& str)
{
	char d[900];
	in >> d;
	String copy{ d };
	str = copy;
	return in;
}
std::ostream& operator<<(std::ostream& out, String& str)
{
	return 	out << str.str;
}
class BiteString:public String
{
public:
	BiteString(const String& copy) :String(copy) { perevirka(); };
	BiteString() :BiteString("") {};
	BiteString(const BiteString& copy) :String(copy){};
	~BiteString() { delete[] str; }
	void perevirka()
	{
		for (int i = 0; i < getSize(); ++i)
		{
			if ((str[i] != '1')and(str[i] != '0'))
			{
				clear();
			}
		}
	}
};
int main()
{
	BiteString str{ "00001" }, str2{ "00000" };
	std::cout << str;
}