#include <iostream>
#include <algorithm>
#include <list>


struct EncChar
{
	enum Idx { start =  0 , count = sizeof("%XX") };
	typedef char HolderType[count];
	EncChar() { m_text[ 0 ] =  0 ; }
	char const* ToString() const { return m_text; }
	void operator =(HolderType const &a) { memmove(m_text, a, count); }
	void operator =(char const x) { m_text[ 0 ] = x, m_text[ 1 ] =  0 ; }

private:
	HolderType m_text;
};

struct HtmlEncode 
{
	EncChar operator ()(char x) const
	{
		EncChar enc;
		switch (x)
		{
		case '\n':
			enc = "%0A";
			break;

		case ';':
			enc = "%3B";
			break;

		case 'd':
			enc = "XXX";
			break;

		default:
			enc = x;
		}
		return enc;
	}
};


int main()
{
	using namespace std;

	string s = "as\r\rdfg\nhadf;gag";
	printf("s = \"%s\"\n", s.c_str());
	list< EncChar > t;
	transform(s.begin(), s.end(), back_inserter(t), HtmlEncode());
	string s_new;
	s_new.reserve(s.size() *  2 );
	for (list< EncChar >::const_iterator i_enc = t.begin(); i_enc != t.end(); ++i_enc) {
		s_new.append(i_enc->ToString());
	}

	printf("s_new = \"%s\"\n", s_new.c_str());
	system("pause");
}

#include <iostream>
#include <algorithm>
#include <iterator>


struct EncChar
{
	enum Idx { count = sizeof("%XX") };
	typedef char HolderType[count];
	EncChar() { m_text[ 0 ] =  0 ; }
	char const* ToString() const { return m_text; }
	void operator =(HolderType const &a) { memmove(m_text, a, count); }
	void operator =(char const x) { m_text[ 0 ] = x, m_text[ 1 ] =  0 ; }

private:
	HolderType m_text;
};

struct HtmlEncode 
{
	EncChar operator ()(char x) const
	{
		EncChar enc;
		switch (x)
		{
		case '\n':
			enc = "%0A";
			break;

		case ';':
			enc = "%3B";
			break;

		case 'd':
			enc = "XXX";
			break;

		default:
			enc = x;
		}
		return enc;
	}
};

class InsEncodedIterator
	: public std::iterator< std::output_iterator_tag, void, void, void, void >
{	
public:
	explicit InsEncodedIterator(std::string &s) : m_ps(&s) {}
	InsEncodedIterator& operator =(EncChar const &v) { m_ps->append(v.ToString()); return (*this); }
	InsEncodedIterator& operator *() { return (*this); }
	InsEncodedIterator& operator ++() { return (*this); }
	InsEncodedIterator operator ++(int) { return (*this); }

protected:
	std::string *m_ps;
};


int main()
{
	using namespace std;

	string s = "as\r\rdfg\nhadf;gag", s_new;
	printf("s = \"%s\"\n", s.c_str());
	s_new.reserve(s.size() *  2 );
	transform(s.begin(), s.end(), InsEncodedIterator(s_new), HtmlEncode());

	printf("s_new = \"%s\"\n", s_new.c_str());
	system("pause");
}

int main()
{
	using namespace std;

	string s = "as\ndfg\nhadf;gag";
	printf("s = \"%s\"\n", s.c_str());
	{
		string s_enc;
		s_enc.reserve(s.size() *  2 );
		transform(s.begin(), s.end(), InsEncodedIterator(s_enc), HtmlEncode());
		s.swap(s_enc);
	}
	printf("s = \"%s\"\n", s.c_str());
	system("pause");
}