main.cpp(string)

※main.cpp파일

#include <iostream>

#include "string.h"



int main()

{

	String s1;

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

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

	String s4 = "aaa";

	String s5 = "bbb";

	

	s1 = s2;

	

	if (s1 == s2) {

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

	} else {

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

	}

	

	s1 = s4+s5;

	

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

	std::cout << "s1 len : " << s1.size() << std::endl;

	

	std::cout << "s1 : " << s1 << std::endl;

	std::cout << "s2 : " << s2 << std::endl;

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

	std::cout << "s4 : " << s4 << std::endl;

	return 0;

}

※string.h파일

#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;

public:

	String();

	String(const char *str);

	String(const String& rhs);

	~String();

	

	String& operator=(const String& rhs);

	bool operator==(const String& rhs);

	const String operator+(const String& rhs);

	

	const char*c_str(); // str값을 리턴

	int size();

};



#endif

※string.cpp파일

#include "string.h"

#include <cassert>

#include <cstring>



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

	out << rhs.str;

	return out;

}



String::String() {

	this->str = new char[1];

	assert(this->str);

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

	this->len = 0;

}



String::String(const char *str){

	this->str=new char[strlen(str) + 1];  // '\0'문자도 포함

	assert(this->str);

	

	strcpy(this->str,str);

	this->len = strlen(str);

}



String::String(const String& rhs){

	this->str=new char[strlen(rhs.str) + 1];  // '\0'문자도 포함

	assert(this->str);

	

	strcpy(this->str,rhs.str);

	this->len = strlen(rhs.str);

}



String::~String(){

	delete[] this->str;

}



const char *String::c_str()

{

	return this->str;

}



int String::size() {

	return this->len;

}



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

	delete[] this->str;

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

	assert(this->str);

	strcpy(this->str, rhs.str);

	this->len = strlen(rhs.str);

	return *this;

}



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

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

}



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

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

	strcpy(buf,this->str);

	strcat(buf,rhs.str);

	String result(buf);

	return result;

}