#include<iostream.h>
#include<graphics.h>
#include<conio.h>
void main()
{
    int gd = DETECT, gm;
    float x1,x2,y1,y2;
    clrscr();
    cout<<"Enter x1 y1 x2 y2: ";
    cin>>x1>>y1>>x2>>y2;
    initgraph(&gd,&gm,"C:/TURBOC3/BGI");
    int dx = x2-x1, dy = y2 - y1;
    if(dx>=dy)
    {
        for(int i=0;i<=dx;i++)
        {
            putpixel(x1,y1,WHITE);
            x1++;
            y1 = y1 + (dy/dx);
        }
    }
    else
    {
        for(int i=0;i<=dy;i++)
        {
            putpixel(x1,y1,WHITE);
            x1 = x1 + (dx/dy);
            y1++;
        }
    }
    getch();
    closegraph();
}

#include<iostream.h>
#include<graphics.h>
#include<conio.h>
void main()
{
    int gd=DETECT,gm,x1,x2,y1,y2,p,dy,dx;
    clrscr();
    cout<<"Enter x1 y1 x2 y2: ";
    cin>>x1>>y1>>x2>>y2; 
    initgraph(&gd,&gm,"C:/TURBOC3/BGI");
    dy = y2-y1;
    dx = x2-x1;
    p = (2*dy) - dx;
    if((dy/dx)<1)
    {
        for(int i=0;i<=dx;i++)
        {
            putpixel(x1,y1,WHITE);
            if(p<0)
            {
                x1++;
                p = p + (2*dy);
            }
            else
            {
                x1++;
                y1++;
                p = p + (2*dy) - (2*dx);
            }
        }
    }
    else
    {
        for(int i=0;i<=dy;i++)
        {
            putpixel(x1,y1,WHITE);
            if(p<0)
            {
                y1++;
                p = p + (2*dx);
            }
            else
            {
                x1++;
                y1++;
                p = p + (2*dx) - (2*dy);
            }
        }
    }
    getch();
    closegraph();
}