12. String 클래스의 디자인

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출처: 윤성우 열혈강의 C++ 예제코드

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12.1. C++ 표준과 표즌 string 클래스

• 표준 string 클래스 이용하기

#include <iostream>
#include <string>
using namespace std;

int main(void)
{
	string str1="I like ";
	string str2="string class";
	string str3=str1+str2;

	cout<<str1<<endl;
	cout<<str2<<endl;
	cout<<str3<<endl;

	str1+=str2;
	if(str1==str3) 	
		cout<<"동일 문자열!"<<endl;
	else
		cout<<"동일하지 않은 문자열!"<<endl;

	string str4;
	cout<<"문자열 입력: ";
	cin>>str4;
	cout<<"입력한 문자열: "<<str4<<endl;
	return 0;
}

I like
string class
I like string class
동일 문자열!
문자열 입력: hello sting
입력한 문자열: hello

12.2. 문자열 처리 클래스의 정의

• 사용자정의 String 클래스 만들기

#include <iostream>
#include <cstring>
using namespace std;

class String
{
private:
	int len;
	char * str;
public:
	String();
	String(const char * s);
	String(const String& s);
	~String();
	String& operator= (const String& s);
	String& operator+= (const String& s);
	bool operator== (const String& s);
	String operator+ (const String& s);

	friend ostream& operator<< (ostream& os, const String& s);
	friend istream& operator>> (istream& is, String& s);
};

String::String()
{
	len=0;
	str=NULL;
}

String::String(const char* s)
{
	len=strlen(s)+1;
	str=new char[len];
	strcpy(str, s);
}

String::String(const String& s)
{
	len=s.len;
	str=new char[len];
	strcpy(str, s.str);
}

String::~String() 
{
	if(str!=NULL)
		delete []str; 
}

String& String::operator= (const String& s)
{
	if(str!=NULL)
		delete []str;
	len=s.len;
	str=new char[len];
	strcpy(str, s.str);
	return *this;
}

String& String::operator+= (const String& s)
{
	len+=(s.len-1);
	char* tempstr=new char[len];
	strcpy(tempstr, str);
	strcat(tempstr, s.str);

	if(str!=NULL)
		delete []str;
	str=tempstr;
	return *this;
}

bool String::operator== (const String& s)
{
	return strcmp(str, s.str) ? false : true;
}

String String::operator+ (const String& s)
{
	char* tempstr=new char[len+s.len-1];
	strcpy(tempstr, str);
	strcat(tempstr, s.str);
	
	String temp(tempstr);
	delete []tempstr;
	return temp;
}

ostream& operator<< (ostream& os, const String& s)
{
	os<<s.str;
	return os;
}

istream& operator>> (istream& is, String& s)
{
	char str[100];
	is>>str;
	s=String(str);
	return is;
}

int main(void)
{
	String str1="I like ";
	String str2="string class";
	String str3=str1+str2;

	cout<<str1<<endl;
	cout<<str2<<endl;
	cout<<str3<<endl;

	str1+=str2;
	if(str1==str3) 	
		cout<<"동일 문자열!"<<endl;
	else
		cout<<"동일하지 않은 문자열!"<<endl;

	String str4;
	cout<<"문자열 입력: ";
	cin>>str4;
	cout<<"입력한 문자열: "<<str4<<endl;
	return 0;
}