#include<stdio.h>
#include<graphics.h>
#include<math.h>
void main()
{
 int x1,x2,y1,y2,gd=DETECT,gm;
 clrscr();
 initgraph(&gd,&gm,"");
 cleardevice();
 gotoxy(1,2);
 printf("\n\t\tDIGITAL DIFFERENTIAL ALGORITHM FOR LINE DRAWING");
 gotoxy(5,5);
 printf("enter co-rodinates of the x1,y1:");
 scanf("%d%d",&x1,&y1);
 gotoxy(5,7);
 printf("enter co-ordinates of x2,y2:");
 scanf("%d%d",&x2,&y2);
 cleardevice();
 DDA(x1,y1,x2,y2);
 getch();
 closegraph();
}
DDA(int X1,int Y1,int X2,int Y2)
{
 int len,i;
 float xin,yin,x,y;
 x=X1+0.8    ;
 y=Y1+0.8;
 len=abs(Y2-Y1);


 if(len<abs(X2-X1))
      len=abs(X2-X1);
 xin=(float)(X2-X1)/len;
 yin=(float)(Y2-Y1)/len;
 for(i=1;i<=len;i++)
 {
     putpixel(abs(x),abs(y),987);
     x+=xin;
     y+=yin;
 }
}