C++ 기본1

생성자,소멸자, 멤버 이니셜라이저.

 

https://musket-ade.tistory.com/entry/C-%EC%83%9D%EC%84%B1%EC%9E%90%EC%99%80-%EC%86%8C%EB%A9%B8%EC%9E%90-%EA%B7%B8%EB%A6%AC%EA%B3%A0-%EB%A9%A4%EB%B2%84-%EC%9D%B4%EB%8B%88%EC%85%9C%EB%9D%BC%EC%9D%B4%EC%A0%80-Member-Initializer

[ C++ ] 생성자와 소멸자 그리고 멤버 이니셜라이저( Member Initializer )

 

https://morning97.tistory.com/37?category=1001665 

[c++] const함수와 멤버이니셜라이저(+this)

TV)

#include<iostream>
using namespace std;

class TV {
private:
	const int PRICE;
	int ch;
	int vol;
	bool power;

public:
	TV(int ch, int vol, int price);  //이니셜라이저 할 생성자 함수 선언
	~TV();
	
	void powerOn(void);
	void powerOff(void);
	void setTv(int ch, int vol); // price는 const떄매 수정 못함, 수정 시 에러.
	void showTvInform(void);
};

TV::TV(int ch, int vol, int price) : PRICE(price) //이니셜라이저
{
	{
		cout << "생성자 생성" << endl;
		this->ch = ch;
		this->vol = vol;
		this->power = false;
	}
}
void TV::powerOn(void)
{
	cout << "==========TV ON==========" << endl;
	power = true;
}

void TV::powerOff(void)
{
	cout << "==========TV OFF==========" << endl;
	power = false;
}

TV::~TV(void)
{
	cout << "생성자 소멸" << endl;
}
void TV::showTvInform(void)
{
	cout << "channel: " << ch << endl;
	cout << "volume: " << vol << endl;
	cout << "price: " << PRICE << endl;
	cout << "전원여부: " << power << endl;
}
void TV::setTv(int ch, int vol)
{
	this->ch = ch;
	this->vol = vol;
}

int main(void)
{
	TV tv(3, 10, 1000);
	tv.powerOn();
	tv.showTvInform();
	tv.setTv(5, 100);
	tv.showTvInform();
	tv.powerOff();
	tv.showTvInform();
}

 

---

 

사각형 넓이 예제 ( 내 코드 ) // 멤버이니셜라이저 사용을 못했음. 익숙해지자.

#include<iostream>
using namespace std;

class Rect
{
private:
	double x1;
	double x2;
	double y1;
	double y2;
	double width;
	double height;
public:
	Rect(double x1, double x2, double y1, double y2)
	{
		this->x1 = x1;
		this->x2 = x2;
		this->y1 = y1;
		this->y2 = y2;
	}
	void showRect()
	{
		cout << "width: " <<(int) width << endl;
		cout << "height: " << (int)height << endl;
	}
	double Area()
	{
		this->width = y2 - y1;
		this->height = x2 - x1;

		return width*height;
	}
};

int main(void)
{
	Rect rectangle(10, 20, 5, 20);
	rectangle.Area();
	rectangle.showRect();
	
	cout << "면적" << endl;
	cout << rectangle.Area()<<endl;
	system("pause");
}

 

모범 코드(예제 그대로)

#include<iostream>

using namespace std;

class Point {
private: 
	int x;
	int y;
public:
	Point(int x, int y)
	{
		this->x = x;
		this->y = y;
	}
	int getX() const
	{
		return x; 
	}
	int getY()const
	{
		return y;
	}
};

class Rectangle {
private:
	Point lowLeft;
	Point upRight;

public:
	Rectangle(int x1, int y1, int x2, int y2):lowLeft(x1,y1),upRight(x2,y2){} // Rectangle클래스의 int x1, x2 ...인자들이 Point 클래스의 lowLeft, upRight 인자들 x1,y1,x2,y2에 할당됨
	int getRectArea()const
	{
		int width = upRight.getX() - lowLeft.getX();
		int height = upRight.getY() - lowLeft.getY();
		// 절댓값
		if (width < 0)
			width =- width;
		if (height < 0)
			height= - height;
		return width*height;
	}
};

int main(void)
{
	Rectangle nemo(10, 10, 5, 20);
	cout << "면적: " << nemo.getRectArea() << endl;
	system("pause");
}