write a program to draw line using DDA line algorithm in c

#include<stdio.h>
#include<conio.h>
#include<graphics.h>
#include<math.h>
void main()
{
 int x,y,xi,yi,x1,y1,y2,x2,i,s;
clrscr();
 int gd=DETECT,gm;
 initgraph(&gd,&gm,"C:\\tc\\")

 printf("enter value of x1:");
 scanf("%d",&x1);
 printf("enter value of y1:");
 scanf("%d",&y1);
  printf("enter value of x2:");
 scanf("%d",&x2);
 printf("enter value of y2:");
 scanf("%d",&y2);

 dx=x2-x1;
 dy=y2-y1;

 if(abs(dx)>abs(dy))
 {
  s=abs(dx);

 }
 else{
  s=abs(dy);
 }

 xi=dx/s;
 yi=dy/s;

 x=xi;
 y=yi;

 putpixel(xi,yi,4);
    for(i=0;i<s;i++)
    {
     x+=x1;
     y+=y1;
   
     putpixel(x1,y1,4);
   
 }
 closegraph();
 getch();
}