DDA Line Drawing Algo

#include<iostream.h>
#include<conio.h>
#include<math.h>
#include<graphics.h>
#include<stdio.h>
void main()
{
 int gdriver=DETECT,gmode;
 initgraph(&gdriver,&gmode,"C:\\TURBOC3\\BGI");

 int x1=50,y1=100,x2=100,y2=300,dx,dy,length;
 int i=1;
 float x,y,xi,yi;
/* cout<<"Enter Starting Point:";
 cin>>x1>>y1;
 cout<<"Enter Ending Point :";
 cin>>x2>>y2;*/
 dx=x2-x1;
 dy=y2-y1;
 if(abs(dx)>abs(dy))
  length=abs(dx);
 else
  length=abs(dy);
xi=(float)dx/length;
yi=(float)dy/length;

x=x1;
y=y1;
 putpixel(x,y,WHITE);
while(i<=length)
 {
 x=x+xi;
 y=y+yi;
 i++;
  putpixel(int(x),int(y),WHITE);
 }
 getch();
 closegraph();
}