String (클래스 개선)

<main.cpp>

#include <iostream>

#include "string.h"



int main()

{

	String s1;

	String s2 = "hello, world";          // String s2("hello, world");

	//String s2 = 0;

	String s3 = s2;                      // String s3(s2);

	

	s1 = s2;

	// s1 = s1;          // self assignment??

	s1 = "hello, ";      // String tmp("hello, "); s1 = tmp; tmp.~String();

	

	String s4 = " IoT";

	s1 = s2 + s4;

	

	if (s1 == s2)

	{

		std::cout << "s1 and s2 are equal" << std::endl;

	}

	else

	{

		std::cout << "s1 and s2 are not equal" << std::endl;

	}

	

	s4 += s4;

	s1 != s2;

	

	std::cout << "s1 : " << s1.c_str() << std::endl;

	std::cout << "s2 : " << s2.c_str() << std::endl;

	std::cout << "s2 len : " << s2.size() << std::endl;

	

	std::cout << s3 << std::endl;

	

	const String s5 = "hello";

	//s5 = "world";

	std::cout << "s3 len : " << s5.size() << std::endl;



	return 0;

}

 

<string.h>

#ifndef STRING_H

#define STRING_H

#include <iostream>



class String {

friend std::ostream& operator<<(std::ostream& out, const String& rhs);



private:

	char *str;

	int len;

	

	void init_str(const char *str);     // tool func. helper func.

	

	String(char *str, bool b);



public:

	//String();

	String(const char *str = 0);

	String(const String& rhs);

	~String();

	

	String& operator=(const String& rhs);

	String& operator=(const char *str);

	

	String& operator+=(const String& rhs);

	

	bool operator==(const String& rhs) const;          // const member func.

	bool operator!=(const String& rhs) const;

	

	// +

	

	const String operator+(const String& rhs) const;

	

	const char *c_str() const;

	int size() const;

};



#endif

 

<string.cpp>

#include "string.h"

#include <cassert>

#include <cstring>



std::ostream& operator<<(std::ostream& out, const String& rhs)

{

	return out << rhs.str;

}



void String::init_str(const char *str)

{

	if (str )

	{

		this->str = new char[strlen(str) + 1];

		assert(this->str );

		

		strcpy(this->str, str);

		this->len = strlen(str);

	}

	else

	{

		this->str = new char[1];

		assert(this->str );

		

		this->str[0] = '\0';

		this->len = 0;

	}

}



/*

String::String()

{

	//this->str = 0;	

	

	this->str = new char[1];

	assert(this->str );

	

	this->str[0] = '\0';

	this->len = 0;

}

*/

String::String(char *str, bool b)

{

	this->str = str;

	this->len = strlen(str);

}



String::String(const char *str)

{

	this->init_str(str);

}



String::String(const String& rhs) {



	this->init_str(rhs.str);



}



String::~String()

{

	//if (this->str )

		delete [] this->str;

}



String& String::operator=(const String& rhs)

{

	if (this != &rhs)          // self-assignment test!

	{

		delete [] this->str;

		

		this->init_str(rhs.str);

	}

	

	return *this;

}



String& String::operator=(const char *str)

{

	if (this->str != str)

	{	

		delete [] this->str;

		

		this->init_str(str);

	}

	

	return *this;

}



String& String::operator+=(const String& rhs)

{

	*this = *this + rhs;

	

	return *this;

}



bool String::operator==(const String& rhs) const

{

	return strcmp(this->str, rhs.str) == 0;

}



bool String::operator!=(const String& rhs) const

{

	return !this->operator==(rhs);

}



const String String::operator+(const String& rhs) const

{

	char *buf = new char[this->len + rhs.len + 1];

	assert(buf );

	strcpy(buf, this->str);

	strcat(buf, rhs.str);

	

	String result(buf, true);

	//delete [] buf;

	

	return result;

}



const char *String::c_str() const

{

	return this->str;

}



int String::size() const

{

	return this->len;

}

 

<compile 결과>