DDA (Digital Differential Analyzer ) line draw algorithm

#include<stdio.h>
#include<graphics.h>
#include<math.h>

#define Round(x) ((int)(x+0.5))

void ddaLine(float x1,float y1,float x2,float y2)
{
  int dx,dy,length,i=1;
  float x=x1,y=y1,xIncr,yIncr;
     dx=abs(x2-x1);
     dy=abs(y2-y1);

  if(dx>=dy)
   length=dx;
 else
   length=dy;

     xIncr=dx/(float)length;
     yIncr=dy/(float)length;

     putpixel(Round(x),Round(y),RED);
     while(i<=length)
     {
 delay(100);
 x+=xIncr;
 y+=yIncr;
 putpixel(Round(x),Round(y),RED);
 i++;
     }

}

int main()
{
 float x1,y1,x2,y2;
 int gdriver = DETECT, gmode, errorcode;
 clrscr();

 initgraph(&gdriver,&gmode,"C://TurboC3//BGI");

 printf("\nEnter the value of x1 :\t");
 scanf("%f",&x1);
 printf("\nEnter the value of y1 :\t");
 scanf("%f",&y1);
 printf("\nEnter the value of x2 :\t");
 scanf("%f",&x2);
 printf("\nEnter the value of y2 :\t");
 scanf("%f",&y2);

 ddaLine(x1,y1,x2,y2);
getch();
closegraph();
return 0;
}