Bresenham's Algorithm for Line.

#include<conio.h>
#include<graphics.h>
#include<iostream.h>
#include<dos.h>

void main()
{clrscr();
int dx,dy,x,y,e,x1,y1,x2,y2;
int gd=DETECT,gm;
initgraph(&gd,&gm,"c:\\TC\\bgi");
cout<<"Enter the co-ordinates of first point : ";
cin>>x1>>y1;
cout<<"Enter the co-ordinates of second point : ";
cin>>x2>>y2;
dx = (x2 - x1);
dy = (y2 - y1);
e = 2 * (dy) - (dx);
x = x1;
y = y1;
putpixel(x,y,15);
while(x <= x2)
{
if(e < 0)
{
x=x+1;
y=y;
e = e + 2 * (dy);
}
else
{
x=x+1;
y=y+1;
e = e + 2 * (dy - dx);
}
putpixel(x,y,WHITE);
delay(20);
}
getch();
}