DDA LINE DRAWING PROGRAM IN C

//***PROGRAM FOR DDA LINE DRAWING ALGORITHM***//

#include<stdio.h>
#include<conio.h>
#include<graphics.h>
#include<dos.h>
#include<process.h>
#include<math.h>
#define ROUND(a) ((int)(a+1))
void lineDDA(int xa,int ya, int xb, int yb)
{
   int dx= xb-xa, dy=yb-ya,steps, k;
   float xIncrement,yIncrement,x=xa,y=ya;
   if(abs(dx)>abs(dy)) steps= abs(dx);
   else steps= abs (dy);
   xIncrement = dx/(float) steps;
   yIncrement = dy/(float) steps;
   putpixel (ROUND(x),ROUND (y),5);
   for (k=0;k<steps;k++)
   {
    x+=xIncrement;
    y+=yIncrement;
    putpixel(ROUND(x),ROUND(y),5);
   }
}

void main()
{
 int a1,a2,b1,b2;
 int gdriver= DETECT, gmode;
 initgraph (&gdriver,&gmode,"c:\tc\bgi");
 printf("ENTER THE STARTING POSITION");
 scanf("%d%d",&a1,&a2);
 printf("ENTER THE ENDING POSITION");
 scanf("%d%d",&b1,&b2);
 lineDDA(a1,b1,a2,b2);
 getch();
 closegraph();
 getch();
}