一 继承访问权限测试

1 代码实现

#ifndef CSHAPE_H
#define CSHAPE_H
class A
{
public:int _a;
protected:int _b;
private:int _c;
};
class Pub_B :public A {
public:void Test() {_a = 10;_b = 10;//_c = 10;不可访问}int pub_pub_b1;
protected:int pub_pro_b2;
private:int pub_pri_b3;
};
class Pro_B :protected A {
public:void Test() {_a = 10;_b = 10;//_c = 10;不可访问}int pro_pub_b1;
protected:int pro_pro_b2;
private:int pro_pri_b3;
};
class Pri_B :private A {
public:void Test() {_a = 10;_b = 10;//_c = 10;不可访问}int pri_pub_b1;
protected:int pri_pro_b2;
private:int pri_pri_b3;
};
class newPri_B :private A {
public:void Test() {_a = 10;_b = 10;//_c = 10;不可访问}int pri_pub_b1;using A::_a;
protected:int pri_pro_b2;
private:int pri_pri_b3;
};#endif

2 小结

• B以private方式继承A，用{using A::_a; }把A中的部分private成员提升为public
• using重新声明。using声明语句中名字的访问权限由该using声明语句之前的访问说明符决定。

• 不允许对不可访问的基类A进行转换

二 友元类继承测试

1 代码实现

#include<istream>
using namespace std;
class A {
private:int _a;friend class C;
};
class B: public A {
private:int _b;
};
class C {
public:void Test() {B b1;b1._a;//b1._b; 不可访问}
};
class D :public C {
public:void Test() {A a1;//a1._a;不可访问B b2;//b2._a;不可访问//b2._b;不可访问}
};

2 小结

• 当类C被说明为类A的友元时 友元类C中的所有成员函数都可以访问类A中的所有成员（包括私有成员）。
• 类B继承类A，但类A对类C友元，类B对类C不友元；类D继承类C，但类A对类C友元，类A对类D不友元。即友元不被继承。

三 多态性综合运用

1 代码实现

1 main.cpp

#include<vector>
#include "graphics.h"
#include<iostream>
#include "CShape.h"
using namespace std;int main()
{//图形画布基础设置initgraph(640, 480);setbkcolor(WHITE);delay_ms(0);setcolor(BLACK);setfont(20, 0, "楷体");setbkmode(TRANSPARENT);//enter+左击-->新建矩形");//enter+右击-->新建三角形");//enter+滚轮中间-->新建组合图形//ctrl+左击-->复制图形");//ctrl+右击-->粘贴图形");vector<CShape*>shapes;vector<CShape*>shapestmp;shapes.push_back(new CTriangle(CPoint(320, 320), CPoint(250, 340), CPoint(340, 450)));//shapes.push_back(new CTriangle(CPoint(10, 10), CPoint(150, 10), CPoint(150, 150)));shapes.push_back(new CRect(CPoint(200, 200), CPoint(300, 300)));shapes.push_back(new Comgraphics(CRect(CPoint(250, 50))));//移动bool move_flag = false;bool copy_flag = false;bool redraw = true;//鼠标点击时记录它的坐标int clickX, clickY;int copyX, copyY;int checkedid = -1;int copyid = -1;for (; is_run(); delay_fps(60)) {while (mousemsg()) {mouse_msg msg = getmouse();//判断鼠标的移动if (msg.is_move()) {if (checkedid != -1) {if (move_flag) {shapes[checkedid]->Move(msg.x - clickX, msg.y - clickY);}}clickX = msg.x;clickY = msg.y;redraw = true;}// 判断鼠标左键else if (msg.is_left()) {// 判断鼠标左键是否按下if (msg.is_down()) {clickX = msg.x;clickY = msg.y;CPoint pt = CPoint(clickX, clickY);int isIn = 0;for (int i = 0; i < shapes.size(); i++) {if (shapes[i]->ptIn(pt)) {isIn = 1;//如果鼠标在图形区域内就设置移动的flag为truemove_flag = true;checkedid = i;redraw = true;break;}}if (isIn == 0)checkedid = -1;}else {move_flag = false;}}}// 重新绘图if (redraw) {redraw = false;cleardevice();for (int i = 0; i < shapes.size(); i++) {if (i == checkedid)shapes[i]->DrawColor();elseshapes[i]->Draw();}}while (kbmsg()) {key_msg msgk = getkey();if (msgk.key == key_enter && msgk.msg == key_msg_down) {mouse_msg msgm = getmouse();if (msgm.is_left()) {// 判断鼠标左键是否按下if (msgm.is_down()) {shapes.push_back(new CRect(CPoint(msgm.x, msgm.y)));redraw = true;}}if (msgm.is_right()) {// 判断鼠标右键是否按下if (msgm.is_down()) {shapes.push_back(new CTriangle(CPoint(msgm.x, msgm.y)));redraw = true;}}if (msgm.is_mid()) {CRect r1 = CRect(CPoint(msgm.x, msgm.y));// 判断鼠标中键是否按下if (msgm.is_down()) {shapes.push_back(new Comgraphics(r1));redraw = true;}}}if (msgk.key == key_control && msgk.msg == key_msg_down) {mouse_msg msgm = getmouse();if (msgm.is_left()) {// 判断鼠标左键是否按下if (msgm.is_down()) {copyX = msgm.x;copyY = msgm.y;CPoint pt = CPoint(copyX, copyY);for (int i = 0; i < shapes.size(); i++) {if (shapes[i]->ptIn(pt)) {//如果鼠标在图形区域内就设置移动的flag为truecopy_flag = true;copyid = i;break;}}}}if (msgm.is_right()) {// 判断鼠标右键是否按下if (msgm.is_down()) {if (copy_flag == true) {shapes.push_back(&(shapes[copyid]->Clone())->Move(msgm.x - copyX, msgm.y - copyY));redraw = true;}}}}}}closegraph();return 0;
}

2.CShape.h

#include "CShape.h"
#include "graphics.h"
#include <iostream>
using namespace std;
//CShape
CShape::CShape()
{
}
CShape::CShape(const CShape& shape) {m_sName = shape.m_sName;
}
CShape::~CShape()
{
}
double CShape::GetArea() const {return 0;
}
bool CShape::ptIn(const CPoint& pt) const {return false;
}
bool CShape::InRect(const CRect& rc) const {return false;
}
void CShape::Draw() const
{
}
void CShape::DrawColor()
{
}
CShape* CShape::Clone() const {return new CShape(*this);
}
CShape& CShape::Move(int nOffsetX, int nOffsetY) {return *this;
}//CPoint
CPoint::CPoint(int nPosX, int nPosY) {m_nPosX = nPosX;m_nPosY = nPosY;
}
CPoint::CPoint(const CPoint& pt) {m_nPosX = pt.m_nPosX;m_nPosY = pt.m_nPosY;
}
CPoint::~CPoint() {//cout << "CPoint::~CPoint()\n";
}
double CPoint::GetArea() const {return 0;
}
bool CPoint::ptIn(const CPoint& pt) const {return false;
}
bool CPoint::InRect(const CRect& rc) const {return rc.ptIn(*this);
}
void CPoint::Draw() const {circle(m_nPosX, m_nPosY, 2);
}
void CPoint::DrawColor()
{
}
CPoint* CPoint::Clone() const {return new CPoint(*this);
}
CPoint& CPoint::Move(int nOffsetX, int nOffsetY) {m_nPosX += nOffsetX;m_nPosY += nOffsetY;return *this;
}//CTriangle
CTriangle::CTriangle(const CTriangle& tri) {for (int i = 0; i < 3; i++) {m_pts[i] = tri.m_pts[i];}
}
CTriangle::~CTriangle() {//cout << "CTriangle::~CTriangle()\n";
}
CTriangle::CTriangle(const CPoint& pt1, const CPoint& pt2, const CPoint& pt3) {m_pts[0] = pt1;m_pts[1] = pt2;m_pts[2] = pt3;
}
CTriangle::CTriangle(const CPoint& pt)
{CPoint* pt1 = new CPoint(pt.m_nPosX + 100, pt.m_nPosY + 90);CPoint* pt2 = new CPoint(pt.m_nPosX, pt.m_nPosY + 90);m_pts[0] = pt;m_pts[1] = *pt1;m_pts[2] = *pt2;
}CShape& CTriangle::Move(int nOffsetX, int nOffsetY) {for (int i = 0; i < 3; i++) {m_pts[i].Move(nOffsetX, nOffsetY);}return *this;
}
double CTriangle::GetArea() const {int x1, y1, x2, y2, x3, y3;x1 = m_pts[0].m_nPosX;y1 = m_pts[0].m_nPosY;x2 = m_pts[1].m_nPosX;y2 = m_pts[1].m_nPosY;x3 = m_pts[2].m_nPosX;y3 = m_pts[2].m_nPosY;double bottomLine = sqrt(pow(x1 - x2, 2) + pow(y1 - y2, 2));double verticalLine1 = abs((y1 - y2) * x3 - (x1 - x2) * y3 + (x1 - x2) * y2 - (y1 - y2) * x2);double verticalLine2 = sqrt(pow(y1 - y2, 2) + pow(x1 - x2, 2));double verticalLine = verticalLine1 / verticalLine2;return (verticalLine * bottomLine) / 2.0;
}
bool CTriangle::ptIn(const CPoint& pt) const {CTriangle c1 = CTriangle(m_pts[0], m_pts[1], pt);CTriangle c2 = CTriangle(m_pts[1], m_pts[2], pt);CTriangle c3 = CTriangle(m_pts[2], m_pts[0], pt);double totalArea = c1.GetArea() + c2.GetArea() + c3.GetArea();if (totalArea == this->GetArea())return true;elsereturn false;
}
bool CTriangle::InRect(const CRect& rc) const {return rc.ptIn(m_pts[0]) && rc.ptIn(m_pts[1]) && rc.ptIn(m_pts[2]);
}
void CTriangle::Draw() const {int poly[8] = { m_pts[0].m_nPosX ,m_pts[0].m_nPosY,m_pts[1].m_nPosX,m_pts[1].m_nPosY,m_pts[2].m_nPosX,m_pts[2].m_nPosY, m_pts[0].m_nPosX ,m_pts[0].m_nPosY };setfillcolor(EGERGB(0xFF, 0xFF, 0xFF));fillpoly(4, poly);
}
void CTriangle::DrawColor() {int poly[8] = { m_pts[0].m_nPosX ,m_pts[0].m_nPosY,m_pts[1].m_nPosX,m_pts[1].m_nPosY,m_pts[2].m_nPosX,m_pts[2].m_nPosY, m_pts[0].m_nPosX ,m_pts[0].m_nPosY };setfillcolor(EGERGB(0xFF, 0xA5, 0x00));fillpoly(4, poly);
}
CShape* CTriangle::Clone() const {return new CTriangle(*this);
}//CRect
CRect::CRect(CPoint pt1, CPoint pt2) {m_ptLT = CPoint(min(pt1.m_nPosX, pt2.m_nPosX), min(pt1.m_nPosY, pt2.m_nPosY));m_ptBR = CPoint(max(pt1.m_nPosX, pt2.m_nPosX), max(pt1.m_nPosY, pt2.m_nPosY));
}
CRect::CRect(const CRect& rc) {m_ptLT = rc.m_ptLT;m_ptBR = rc.m_ptBR;
}
CRect::CRect(CPoint pt1)
{m_ptLT = CPoint(pt1.m_nPosX, pt1.m_nPosY);m_ptBR = CPoint(pt1.m_nPosX + 100, pt1.m_nPosY + 100);
}
CRect::~CRect() {// cout << "CRect::CRect()\n";
}
double CRect::GetArea() const {return (m_ptBR.m_nPosX - m_ptLT.m_nPosX) * (m_ptBR.m_nPosY - m_ptLT.m_nPosY);
}
bool CRect::ptIn(const CPoint& pt) const {return (pt.m_nPosX >= m_ptLT.m_nPosX && pt.m_nPosX <= m_ptBR.m_nPosX) &&(pt.m_nPosY >= m_ptLT.m_nPosY && pt.m_nPosY <= m_ptBR.m_nPosY);
}
bool CRect::InRect(const CRect& rc) const {return rc.ptIn(m_ptLT) && rc.ptIn(m_ptBR);
}
void CRect::Draw() const {// 存储n个顶点的x,y坐标int pts[10] = { m_ptLT.m_nPosX,m_ptLT.m_nPosY,m_ptBR.m_nPosX,m_ptLT.m_nPosY,m_ptBR.m_nPosX,m_ptBR.m_nPosY,m_ptLT.m_nPosX,m_ptBR.m_nPosY,m_ptLT.m_nPosX,m_ptLT.m_nPosY };// 绘制n个顶点的多边形，第一个参数必须要传入n+1，pts最后一个顶点坐标和第一个相同//drawpoly(5, pts);setfillcolor(EGERGB(0xFF, 0xFF, 0xFF));fillpoly(5, pts);
}
void CRect::DrawColor() {int pts[10] = { m_ptLT.m_nPosX,m_ptLT.m_nPosY,m_ptBR.m_nPosX,m_ptLT.m_nPosY,m_ptBR.m_nPosX,m_ptBR.m_nPosY,m_ptLT.m_nPosX,m_ptBR.m_nPosY,m_ptLT.m_nPosX,m_ptLT.m_nPosY };// 绘制n个顶点的多边形，第一个参数必须要传入n+1，pts最后一个顶点坐标和第一个相同setfillcolor(EGERGB(0xFF, 0xA5, 0x00));fillpoly(5, pts);
}
CShape* CRect::Clone() const {return new CRect(*this);
}
CShape& CRect::Move(int nOffsetX, int nOffsetY) {m_ptLT.Move(nOffsetX, nOffsetY);m_ptBR.Move(nOffsetX, nOffsetY);return *this;}
//Comgraphics
Comgraphics::Comgraphics(const CRect& pt1) {m_pt1.m_nPosX = pt1.m_ptBR.m_nPosX;m_pt1.m_nPosY = pt1.m_ptLT.m_nPosY + (pt1.m_ptBR.m_nPosY - pt1.m_ptLT.m_nPosY) / 2;m_pt2.m_nPosX = pt1.m_ptLT.m_nPosX + (pt1.m_ptBR.m_nPosX - pt1.m_ptLT.m_nPosX) / 2;m_pt2.m_nPosY = pt1.m_ptBR.m_nPosY;m_ptLT = pt1.m_ptLT;m_ptBR = pt1.m_ptBR;}
Comgraphics::Comgraphics(const Comgraphics& rc) {m_pt1 = rc.m_pt1;m_pt2 = rc.m_pt2;m_ptBR = rc.m_ptBR;m_ptLT = rc.m_ptLT;
}
Comgraphics::Comgraphics(const CPoint pt1) {m_ptLT = CPoint(pt1.m_nPosX, pt1.m_nPosY);m_ptBR = CPoint(pt1.m_nPosX + 60, pt1.m_nPosY + 80);
}
Comgraphics::~Comgraphics() {cout << "Comgraphics::~Comgraphics()" << endl;}
double Comgraphics::GetArea()  const {return 0.0;
}
bool Comgraphics::ptIn(const CPoint& pt) const {return (pt.m_nPosX >= m_ptLT.m_nPosX && pt.m_nPosX <= m_ptBR.m_nPosX) &&(pt.m_nPosY >= m_ptLT.m_nPosY && pt.m_nPosY <= m_ptBR.m_nPosY);
}
bool Comgraphics::InRect(const CRect& rc) const const {return rc.ptIn(m_ptLT) && rc.ptIn(m_ptBR);
}
void Comgraphics::Draw() const {// 存储n个顶点的x,y坐标int pts[10] = { m_ptLT.m_nPosX,m_ptLT.m_nPosY,m_ptBR.m_nPosX,m_ptLT.m_nPosY,m_ptBR.m_nPosX,m_ptBR.m_nPosY,m_ptLT.m_nPosX,m_ptBR.m_nPosY,m_ptLT.m_nPosX,m_ptLT.m_nPosY };// 绘制n个顶点的多边形，第一个参数必须要传入n+1，pts最后一个顶点坐标和第一个相同//drawpoly(5, pts);setfillcolor(GREEN);fillpoly(5, pts);line(m_pt1.m_nPosX, m_pt1.m_nPosY, m_pt2.m_nPosX, m_pt2.m_nPosY);line(m_ptLT.m_nPosX, m_ptLT.m_nPosY, m_pt2.m_nPosX, m_pt2.m_nPosY);line(m_pt1.m_nPosX, m_pt1.m_nPosY, m_ptLT.m_nPosX, m_ptLT.m_nPosY);
}
void Comgraphics::DrawColor() {// 存储n个顶点的x,y坐标int pts[10] = { m_ptLT.m_nPosX,m_ptLT.m_nPosY,m_ptBR.m_nPosX,m_ptLT.m_nPosY,m_ptBR.m_nPosX,m_ptBR.m_nPosY,m_ptLT.m_nPosX,m_ptBR.m_nPosY,m_ptLT.m_nPosX,m_ptLT.m_nPosY };// 绘制n个顶点的多边形，第一个参数必须要传入n+1，pts最后一个顶点坐标和第一个相同setfillcolor(YELLOW);fillpoly(5, pts);line(m_pt1.m_nPosX, m_pt1.m_nPosY, m_pt2.m_nPosX, m_pt2.m_nPosY);line(m_ptLT.m_nPosX, m_ptLT.m_nPosY, m_pt2.m_nPosX, m_pt2.m_nPosY);line(m_pt1.m_nPosX, m_pt1.m_nPosY, m_ptLT.m_nPosX, m_ptLT.m_nPosY);
}
CShape* Comgraphics::Clone() const {return new Comgraphics(*(this));
}CShape& Comgraphics::Move(int nOffsetX, int nOffsetY) {m_ptLT.Move(nOffsetX, nOffsetY);m_ptBR.Move(nOffsetX, nOffsetY);m_pt1.Move(nOffsetX, nOffsetY);m_pt2.Move(nOffsetX, nOffsetY);return *this;
}

3.CShape.cpp

#include "CShape.h"
#include "graphics.h"
#include <iostream>
using namespace std;
//CShape
CShape::CShape()
{
}
CShape::CShape(const CShape& shape) {m_sName = shape.m_sName;
}
CShape::~CShape()
{
}
double CShape::GetArea() const {return 0;
}
bool CShape::ptIn(const CPoint& pt) const {return false;
}
bool CShape::InRect(const CRect& rc) const {return false;
}
void CShape::Draw() const
{
}
void CShape::DrawColor()
{
}
CShape* CShape::Clone() const {return new CShape(*this);
}
CShape& CShape::Move(int nOffsetX, int nOffsetY) {return *this;
}//CPoint
CPoint::CPoint(int nPosX, int nPosY) {m_nPosX = nPosX;m_nPosY = nPosY;
}
CPoint::CPoint(const CPoint& pt) {m_nPosX = pt.m_nPosX;m_nPosY = pt.m_nPosY;
}
CPoint::~CPoint() {//cout << "CPoint::~CPoint()\n";
}
double CPoint::GetArea() const {return 0;
}
bool CPoint::ptIn(const CPoint& pt) const {return false;
}
bool CPoint::InRect(const CRect& rc) const {return rc.ptIn(*this);
}
void CPoint::Draw() const {circle(m_nPosX, m_nPosY, 2);
}
void CPoint::DrawColor()
{
}
CPoint* CPoint::Clone() const {return new CPoint(*this);
}
CPoint& CPoint::Move(int nOffsetX, int nOffsetY) {m_nPosX += nOffsetX;m_nPosY += nOffsetY;return *this;
}//CTriangle
CTriangle::CTriangle(const CTriangle& tri) {for (int i = 0; i < 3; i++) {m_pts[i] = tri.m_pts[i];}
}
CTriangle::~CTriangle() {//cout << "CTriangle::~CTriangle()\n";
}
CTriangle::CTriangle(const CPoint& pt1, const CPoint& pt2, const CPoint& pt3) {m_pts[0] = pt1;m_pts[1] = pt2;m_pts[2] = pt3;
}
CTriangle::CTriangle(const CPoint& pt)
{CPoint* pt1 = new CPoint(pt.m_nPosX + 100, pt.m_nPosY + 90);CPoint* pt2 = new CPoint(pt.m_nPosX, pt.m_nPosY + 90);m_pts[0] = pt;m_pts[1] = *pt1;m_pts[2] = *pt2;
}CShape& CTriangle::Move(int nOffsetX, int nOffsetY) {for (int i = 0; i < 3; i++) {m_pts[i].Move(nOffsetX, nOffsetY);}return *this;
}
double CTriangle::GetArea() const {int x1, y1, x2, y2, x3, y3;x1 = m_pts[0].m_nPosX;y1 = m_pts[0].m_nPosY;x2 = m_pts[1].m_nPosX;y2 = m_pts[1].m_nPosY;x3 = m_pts[2].m_nPosX;y3 = m_pts[2].m_nPosY;double bottomLine = sqrt(pow(x1 - x2, 2) + pow(y1 - y2, 2));double verticalLine1 = abs((y1 - y2) * x3 - (x1 - x2) * y3 + (x1 - x2) * y2 - (y1 - y2) * x2);double verticalLine2 = sqrt(pow(y1 - y2, 2) + pow(x1 - x2, 2));double verticalLine = verticalLine1 / verticalLine2;return (verticalLine * bottomLine) / 2.0;
}
bool CTriangle::ptIn(const CPoint& pt) const {CTriangle c1 = CTriangle(m_pts[0], m_pts[1], pt);CTriangle c2 = CTriangle(m_pts[1], m_pts[2], pt);CTriangle c3 = CTriangle(m_pts[2], m_pts[0], pt);double totalArea = c1.GetArea() + c2.GetArea() + c3.GetArea();if (totalArea == this->GetArea())return true;elsereturn false;
}
bool CTriangle::InRect(const CRect& rc) const {return rc.ptIn(m_pts[0]) && rc.ptIn(m_pts[1]) && rc.ptIn(m_pts[2]);
}
void CTriangle::Draw() const {int poly[8] = { m_pts[0].m_nPosX ,m_pts[0].m_nPosY,m_pts[1].m_nPosX,m_pts[1].m_nPosY,m_pts[2].m_nPosX,m_pts[2].m_nPosY, m_pts[0].m_nPosX ,m_pts[0].m_nPosY };setfillcolor(EGERGB(0xFF, 0xFF, 0xFF));fillpoly(4, poly);
}
void CTriangle::DrawColor() {int poly[8] = { m_pts[0].m_nPosX ,m_pts[0].m_nPosY,m_pts[1].m_nPosX,m_pts[1].m_nPosY,m_pts[2].m_nPosX,m_pts[2].m_nPosY, m_pts[0].m_nPosX ,m_pts[0].m_nPosY };setfillcolor(EGERGB(0xFF, 0xA5, 0x00));fillpoly(4, poly);
}
CShape* CTriangle::Clone() const {return new CTriangle(*this);
}//CRect
CRect::CRect(CPoint pt1, CPoint pt2) {m_ptLT = CPoint(min(pt1.m_nPosX, pt2.m_nPosX), min(pt1.m_nPosY, pt2.m_nPosY));m_ptBR = CPoint(max(pt1.m_nPosX, pt2.m_nPosX), max(pt1.m_nPosY, pt2.m_nPosY));
}
CRect::CRect(const CRect& rc) {m_ptLT = rc.m_ptLT;m_ptBR = rc.m_ptBR;
}
CRect::CRect(CPoint pt1)
{m_ptLT = CPoint(pt1.m_nPosX, pt1.m_nPosY);m_ptBR = CPoint(pt1.m_nPosX + 100, pt1.m_nPosY + 100);
}
CRect::~CRect() {// cout << "CRect::CRect()\n";
}
double CRect::GetArea() const {return (m_ptBR.m_nPosX - m_ptLT.m_nPosX) * (m_ptBR.m_nPosY - m_ptLT.m_nPosY);
}
bool CRect::ptIn(const CPoint& pt) const {return (pt.m_nPosX >= m_ptLT.m_nPosX && pt.m_nPosX <= m_ptBR.m_nPosX) &&(pt.m_nPosY >= m_ptLT.m_nPosY && pt.m_nPosY <= m_ptBR.m_nPosY);
}
bool CRect::InRect(const CRect& rc) const {return rc.ptIn(m_ptLT) && rc.ptIn(m_ptBR);
}
void CRect::Draw() const {// 存储n个顶点的x,y坐标int pts[10] = { m_ptLT.m_nPosX,m_ptLT.m_nPosY,m_ptBR.m_nPosX,m_ptLT.m_nPosY,m_ptBR.m_nPosX,m_ptBR.m_nPosY,m_ptLT.m_nPosX,m_ptBR.m_nPosY,m_ptLT.m_nPosX,m_ptLT.m_nPosY };// 绘制n个顶点的多边形，第一个参数必须要传入n+1，pts最后一个顶点坐标和第一个相同//drawpoly(5, pts);setfillcolor(EGERGB(0xFF, 0xFF, 0xFF));fillpoly(5, pts);
}
void CRect::DrawColor() {int pts[10] = { m_ptLT.m_nPosX,m_ptLT.m_nPosY,m_ptBR.m_nPosX,m_ptLT.m_nPosY,m_ptBR.m_nPosX,m_ptBR.m_nPosY,m_ptLT.m_nPosX,m_ptBR.m_nPosY,m_ptLT.m_nPosX,m_ptLT.m_nPosY };// 绘制n个顶点的多边形，第一个参数必须要传入n+1，pts最后一个顶点坐标和第一个相同setfillcolor(EGERGB(0xFF, 0xA5, 0x00));fillpoly(5, pts);
}
CShape* CRect::Clone() const {return new CRect(*this);
}
CShape& CRect::Move(int nOffsetX, int nOffsetY) {m_ptLT.Move(nOffsetX, nOffsetY);m_ptBR.Move(nOffsetX, nOffsetY);return *this;}
//Comgraphics
Comgraphics::Comgraphics(const CRect& pt1) {m_pt1.m_nPosX = pt1.m_ptBR.m_nPosX;m_pt1.m_nPosY = pt1.m_ptLT.m_nPosY + (pt1.m_ptBR.m_nPosY - pt1.m_ptLT.m_nPosY) / 2;m_pt2.m_nPosX = pt1.m_ptLT.m_nPosX + (pt1.m_ptBR.m_nPosX - pt1.m_ptLT.m_nPosX) / 2;m_pt2.m_nPosY = pt1.m_ptBR.m_nPosY;m_ptLT = pt1.m_ptLT;m_ptBR = pt1.m_ptBR;}
Comgraphics::Comgraphics(const Comgraphics& rc) {m_pt1 = rc.m_pt1;m_pt2 = rc.m_pt2;m_ptBR = rc.m_ptBR;m_ptLT = rc.m_ptLT;
}
Comgraphics::Comgraphics(const CPoint pt1) {m_ptLT = CPoint(pt1.m_nPosX, pt1.m_nPosY);m_ptBR = CPoint(pt1.m_nPosX + 60, pt1.m_nPosY + 80);
}
Comgraphics::~Comgraphics() {cout << "Comgraphics::~Comgraphics()" << endl;}
double Comgraphics::GetArea()  const {return 0.0;
}
bool Comgraphics::ptIn(const CPoint& pt) const {return (pt.m_nPosX >= m_ptLT.m_nPosX && pt.m_nPosX <= m_ptBR.m_nPosX) &&(pt.m_nPosY >= m_ptLT.m_nPosY && pt.m_nPosY <= m_ptBR.m_nPosY);
}
bool Comgraphics::InRect(const CRect& rc) const const {return rc.ptIn(m_ptLT) && rc.ptIn(m_ptBR);
}
void Comgraphics::Draw() const {// 存储n个顶点的x,y坐标int pts[10] = { m_ptLT.m_nPosX,m_ptLT.m_nPosY,m_ptBR.m_nPosX,m_ptLT.m_nPosY,m_ptBR.m_nPosX,m_ptBR.m_nPosY,m_ptLT.m_nPosX,m_ptBR.m_nPosY,m_ptLT.m_nPosX,m_ptLT.m_nPosY };// 绘制n个顶点的多边形，第一个参数必须要传入n+1，pts最后一个顶点坐标和第一个相同//drawpoly(5, pts);setfillcolor(GREEN);fillpoly(5, pts);line(m_pt1.m_nPosX, m_pt1.m_nPosY, m_pt2.m_nPosX, m_pt2.m_nPosY);line(m_ptLT.m_nPosX, m_ptLT.m_nPosY, m_pt2.m_nPosX, m_pt2.m_nPosY);line(m_pt1.m_nPosX, m_pt1.m_nPosY, m_ptLT.m_nPosX, m_ptLT.m_nPosY);
}
void Comgraphics::DrawColor() {// 存储n个顶点的x,y坐标int pts[10] = { m_ptLT.m_nPosX,m_ptLT.m_nPosY,m_ptBR.m_nPosX,m_ptLT.m_nPosY,m_ptBR.m_nPosX,m_ptBR.m_nPosY,m_ptLT.m_nPosX,m_ptBR.m_nPosY,m_ptLT.m_nPosX,m_ptLT.m_nPosY };// 绘制n个顶点的多边形，第一个参数必须要传入n+1，pts最后一个顶点坐标和第一个相同setfillcolor(YELLOW);fillpoly(5, pts);line(m_pt1.m_nPosX, m_pt1.m_nPosY, m_pt2.m_nPosX, m_pt2.m_nPosY);line(m_ptLT.m_nPosX, m_ptLT.m_nPosY, m_pt2.m_nPosX, m_pt2.m_nPosY);line(m_pt1.m_nPosX, m_pt1.m_nPosY, m_ptLT.m_nPosX, m_ptLT.m_nPosY);
}
CShape* Comgraphics::Clone() const {return new Comgraphics(*(this));
}CShape& Comgraphics::Move(int nOffsetX, int nOffsetY) {m_ptLT.Move(nOffsetX, nOffsetY);m_ptBR.Move(nOffsetX, nOffsetY);m_pt1.Move(nOffsetX, nOffsetY);m_pt2.Move(nOffsetX, nOffsetY);return *this;
}

2 运行结果

3 小结

• VS中EGE图形行库配置只需下载ege后用其中的include和lib将VS软件中的include和lib替换即可。
• EGE图形行库中的EGE为Easluy Graphics Engine的缩写，是windows下的简易绘图库，是一个类似BGI(graphics.h)的面向C/C++语言新手的图形库，它的目标也是为了替代TC的BGI库而存在。它的使用方法与TC中的graphics.h相当接近。
• 菱形继承（类 A 派生出类 B 和类 C，类 D 继承自类 B 和类 C）时需要使用虚继承，否则访问A的成员变量时，就会产二义性。
• C++的多态特性时，常常会碰到一种情况，就是当指向基类的指针被释放时，派生类的析构函数其实没有被调用，导致在派生类中申请的空间没有被释放，导致内存泄漏。此时，虚析构函数能够有效的防止这种情况的出现。
• .特殊多态性函数：输入或输出参数在子类中是父类的指针或基类的引用，在子类中对于的是子类的指针或子类的引用。
• 一般多态性函数：输入输出参数完全一样，在父类中添加virtual；