SQL with Manoj

Q24. Program to implement Virtual Functions:

Draw the various geometrical figures using the concept of virtual functions along with following class hierarchy:
The base class shapes should contain a virtual function draw().
All the derived classes should contain the function to calculate and display the area of the respective figure.

… from College notes (BCA/MCA assignments):

#include <iostream.h>
#include <graphics.h>
#include <stdlib.h>
#include <conio.h>
#include <math.h>

class Cshapes{
	protected:
		int x1, y1;
	public:
		Cshapes(){}
		virtual void Draw() = 0;
		virtual void Area() = 0;
	};

class Cline : public Cshapes{
	private:
		int x2, y2;
	public:
		Cline(){}
		Cline(int _x1, int _y1, int _x2, int _y2){
			x1 = _x1;
			y1 = _y1;
			x2 = _x2;
			y2 = _y2;
			}
		void Draw(){
			line(x1, y1, x2, y2);
			}
		void Area(){
			cout<<"\n No Area, its a Line.";
			}
	};

class Ctrng : public Cshapes{
	private:
		int x2, y2, x3, y3;
	public:
		Ctrng(){}
		Ctrng(int _x1, int _y1, int _x2, int _y2, int _x3, int 
 _y3){
			x1 = _x1;
			y1 = _y1;
			x2 = _x2;
			y2 = _y2;
			x3 = _x3;
			y3 = _y3;
			}
		void Draw(){
			line(x1, y1, x2, y2);
			line(x2, y2, x3, y3);
			line(x3, y3, x1, y1);
			}
		void Area(){
			unsigned int s1, s2, s3;
			float s, ar;
			s1 = sqrt( pow((x2-x1), 2) + pow((y2-y1), 2) );
			s2 = sqrt( pow((x3-x2), 2) + pow((y3-y2), 2) );
			s3 = sqrt( pow((x3-x1), 2) + pow((y3-y1), 2) );
			s = (s1+s2+s3)/2;
			ar = sqrt(s * (s-s1) * (s-s2) * (s-s3));
			gotoxy(1, 24);
			cout<<" Area of Triangle: "<<ar;
			}
	};

class Crect : public Cshapes{
	private:
		int x2, y2;
	public:
		Crect(){}
		Crect(int _x1, int _y1, int _x2, int _y2){
			x1 = _x1;
			y1 = _y1;
			x2 = _x2;
			y2 = _y2;
			}
		void Draw(){
			line(x1, y1, x1, y2);
			line(x1, y2, x2, y2);
			line(x2, y2, x2, y1);
			line(x2, y1, x1, y1);
			}
		void Area(){
			int ln, bd;
			unsigned long ar;
			ln = abs(x2 - x1);
			bd = abs(y2 - y1);
			ar = ln * bd;
			gotoxy(1, 24);
			cout<<" Area of Rectangle: "<<ar;
			}
	};


void main(){
	int ch, _x1, _y1, _x2, _y2, _x3, _y3;
	int gd=DETECT, gm;
	initgraph(&gd, &gm, "\\tc");

	Cline Oline;
	Ctrng Otrng;
	Crect Orect;
	while(1){
		clrscr();
		cleardevice();
		cout<<"\n 1 -> LINE";
		cout<<"\n 2 -> TRIANGLE";
		cout<<"\n 3 -> RECTANGLE";
		cout<<"\n 4 -> EXIT";
		cout<<"\n Enter your choice: ";
		cin>>ch;
		switch(ch){
			case 1: // LINE.
				cout<<"\n Enter 1st Cordinates: ";
				cin>>_x1>>_y1;
				cout<<"\n Enter 2nd Cordinates: ";
				cin>>_x2>>_y2;
				Cline  Oline(_x1, _y1, _x2, _y2);
				clrscr();
				cleardevice();
				Oline.Draw();
				Oline.Area();
				break;
			case 2: // TRIANGLE.
				cout<<"\n Enter 1st Cordinates: ";
				cin>>_x1>>_y1;
				cout<<"\n Enter 2nd Cordinates: ";
				cin>>_x2>>_y2;
				cout<<"\n Enter 3rd Cordinates: ";
				cin>>_x3>>_y3;
				clrscr();
				cleardevice();
				Ctrng  Otrng(_x1, _y1, _x2, _y2, _x3, _y3);
				Otrng.Draw();
				Otrng.Area();
				break;
			case 3:	// RECTANGLE.
				cout<<"\n Enter 1st Cordinates: ";
				cin>>_x1>>_y1;
				cout<<"\n Enter 2nd Cordinates: ";
				cin>>_x2>>_y2;
				clrscr();
				cleardevice();
				Crect  Orect(_x1, _y1, _x2, _y2);
				Orect.Draw();
				Orect.Area();
				break;
			case 4:	// EXIT
				closegraph();
				exit(1);
			default:
				cout<<"\n Enter Appropriate Choice.";
			} // end of switch.
		getch();
		} // end of while.
	} // end of main.

Output:

DRAW – MAIN MENU

1 -> LINE
2 -> TRIANGLE
3 -> RECTANGLE
4 -> EXIT

Enter your choice: 1

Enter 1st Cordinate: 100 100
Enter 2nd Cordinate: 300 400

No Area, its a Line.