c++-面向对象类的示例-求周长面积，判断体积相等-文件操作和一般操作

面向对象编程示例：求周长和面积

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>


using namespace std;

//圆的周长
double getCircleGirth(double r)
{
	return 2 * 3.14*r;
}

//源的面积
double getCircleArea(double r)
{
	return 3.14*r*r;
}

//用面向对象实现

//圆类
class Circle
{
public:
	void setR(double r)
	{
		m_r = r;
	}

	double getR()
	{
		return m_r;
	}

	double getGirth()
	{
		return 2 * 3.14 *m_r;
	}

	double getArea()
	{
		return m_r*m_r*3.14;
	}

private:
	double m_r; //圆的私有成员 半径
};

class Circle2
{
public:

	void setR(double r)
	{
		m_r = r;
	}

	double getR()
	{
		return m_r;
	}

	double getArea()
	{
		m_area = m_r*m_r*3.14;
		return m_area;
	}

	double getGirth()
	{
		m_girth = m_r * 2 * 3.14;
		return m_girth;
	}

private:
	double m_r;
	double m_girth; //周长
	double m_area;//面积
};


int main(void)
{
	double r = 10; //圆的半径

	double g = 0;
	double a = 0;

	g = getCircleGirth(r);
	a = getCircleArea(r);
	cout << "圆的半径是" << r << endl;
	cout << "圆的周长是" << g << endl;
	cout << "圆的面积是" << a << endl;

	cout << "------" << endl;

	Circle c;

	c.setR(10);

	cout << "圆的半径是" << c.getR() << endl;
	cout << "圆的周长是" << c.getGirth() << endl;
	cout << "圆的面积是" << c.getArea() << endl;

	cout << "------------" << endl;

	Circle2 c2;

	c2.setR(10);


	cout << "圆的半径是" << c2.getR() << endl;
	cout << "圆的周长是" << c2.getGirth() << endl;
	cout << "圆的面积是" << c2.getArea() << endl;

	return 0;
}

上面那个多文件形式（模块化？(^▽)）

main.cpp

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>

#include "Circle.h"

using namespace std;

int main(void)
{
	Circle c;
	c.setR(10);

	cout << "Ãæ»ý" << c.getArea() << endl;


	return 0;
}

Circle.h

#pragma once

#if 0
#ifndef __CIRCLE_H_
#define __CIRCLE_H_


#endif
#endif

class Circle
{
public:
	//ÉèÖð뾶£º
	void setR(double r);
	//µÃµ½°ë¾¶
	double getR();

	double getArea();

	double getGirth();

private:
	double m_r;
	double m_area;
	double m_girth;
};

Circle.cpp

#include "Circle.h"

void Circle::setR(double r)
{
	m_r = r;
}


double Circle::getR()
{
	return m_r;
}

double Circle::getArea()
{
	m_area = m_r *m_r *3.14;

	return m_area;
}

double Circle::getGirth()
{
	m_girth = m_r * 2 * 3.14;

	return m_girth;
}

示例：判断立方体相等

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>


using namespace std;

//立方体类
class Cube
{
public:
	void setABC(int a, int b, int c)
	{
		m_a = a;
		m_b = b;
		m_c = c;
	}

	int getArea()
	{
		return (m_a*m_b) * 2 + (m_a*m_c) * 2 + (m_b*m_c) * 2;
	}

	int getVolume()
	{
		return (m_a*m_b*m_c);
	}

	int getA()
	{
		return m_a;
	}

	int getB()
	{
		return m_b;
	}

	int getC()
	{
		return m_c;
	}

	//同类之间无私处
	bool judgeCube(Cube &another)
	{
		if (m_a == another.m_a &&
			m_b == another.getB() &&
			m_c == another.getC()) {
			return true;
		}
		else {
			return false;
		}
	}
private:
	int m_a;
	int m_b;
	int m_c;
};

//全局函数
bool judgeCube(Cube &c1, Cube &c2)
{
	if (c1.getA() == c2.getA() &&
		c1.getB() == c2.getB() &&
		c1.getC() == c2.getC()) {
		return true;
	}
	else {
		return false;
	}
}

int main(void)
{
	Cube c1;
	c1.setABC(10, 20, 30);

	Cube c2;
	c2.setABC(10, 20, 30);

	cout << "c1 的体积是" << c1.getVolume() << endl;
	cout << "c1 的面积是" << c1.getArea() << endl;

	if (judgeCube(c1, c2) == true) {
		cout << "相等" << endl;
	}
	else {
		cout << "不相等" << endl;
	}
	cout << " ------ " << endl;

	if (c1.judgeCube(c2) == true) {
		cout << "相等" << endl;
	}
	else {
		cout << "不相等" << endl;
	}


	return 0;
}

示例：求点是否在圆内

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>


using namespace std;

//点类
class Point
{
public:
	void setXY(int x, int y)
	{
		m_x = x;
		m_y = y;
	}

	int getX()
	{
		return m_x;
	}

	int getY()
	{
		return m_y;
	}
private:
	int m_x;
	int m_y;
};

//圆类
class Circle
{
public:
	void setXY(int x, int y)
	{
		x0 = x;
		y0 = y;
	}

	void setR(int r)
	{
		m_r = r;
	}

	//提供一个判断点是否在圆内
	//true 在内部
	//false 在外部
	bool judgePoint(Point &p)
	{
		int dd;

		dd = (p.getX() - x0)*(p.getX() - x0) + (p.getY() - y0)*(p.getY() - y0);

		if (dd > m_r*m_r) {
			return false;
		}
		else {
			return true;
		}
	}


private:
	int x0;
	int y0;
	int m_r;
};

int main(void)
{
	Circle c;
	c.setXY(2, 2);
	c.setR(4);

	Point p;
	p.setXY(8, 8);

	if (c.judgePoint(p) == true) {
		cout << "圆的内部" << endl;
	}
	else {
		cout << "圆的外部" << endl;
	}



	return 0;
}

上面代码的文件形式

main.cpp

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include "Circle.h"
#include "Point.h"

using namespace std;

int main(void)
{
	Circle c;
	c.setR(4);
	c.setXY(2, 2);

	Point p;
	p.setXY(8, 8);

	if (c.judgePoint(p) == true) {
		cout << "nei" << endl;
	}
	else {
		cout << "wai" << endl;
	}
	
	return 0;
}

Circle.h

#pragma once
#include "Point.h"

class Circle
{
public:
	void setXY(int x, int y);

	void setR(int r);

	//提供一个判断点是否在圆内
	//true 在内部
	//false 在外部
	bool judgePoint(Point &p);

private:
	int x0;
	int y0;
	int m_r;
};

Circle.cpp

#include "Circle.h"

void Circle::setXY(int x, int y)
{
	x0 = x;
	y0 = y;
}

void Circle::setR(int r)
{
	m_r = r;
}

//提供一个判断点是否在圆内
//true 在内部
//false 在外部
bool Circle::judgePoint(Point &p)
{
	int dd;

	dd = (p.getX() - x0)*(p.getX() - x0) + (p.getY() - y0)*(p.getY() - y0);

	if (dd > m_r*m_r) {
		return false;
	}
	else {
		return true;
	}
}

Point.h

#pragma once


class Point
{
public:
	void setXY(int x, int y);

	int getX();

	int getY();
private:
	int m_x;
	int m_y;
};

Point.cpp

#include "Point.h"


void Point::setXY(int x, int y)
{
	m_x = x;
	m_y = y;
}

int  Point::getX()
{
	return m_x;
}

int Point::getY()
{
	return m_y;
}