#include<stdio.h>
//#include<conio.h>
 #include<graphics.h>
 #include<math.h>
 void dda(float x1,float y1,float x2,float y2)
 {
 float dx,dy,x=x1,y=y1,m;
 int i;
 dx=x2-x1;
 dy=y2-y1;
 if(abs(dx)>=abs(dy))
 m=abs(dx);
 else m=abs(dy);
 putpixel((int)x,(int)y,15);
 for(i=1;i<=m;i++)
 {
  x=x+dx/m;
  y=y+dy/m;
  putpixel((int)x,(int)y,15);
 }
 }
 void bress(float x1,float y1,float x2,float y2)
 {
  int x,y,end,inc=0,p,dx=abs(x2-x1),dy=abs(y2-y1),c=0,current=0;
  if(dx>dy)
  {
   p=2*dy-dx;
    if(x1<x2)
    {
      x=x1;y=y1;end=x2;
      if(y1<y2)inc=1;
      if(y1>y2)inc=-1;
    }
    else
    {
      x=x2;y=y2;end=x1;
      if(y2<y1)inc=1;
     if(y2>y1)inc=-1;
    }
    while(x<=end)
    {
     putpixel(x,y,15);

     if(p<0) p=p+2*dy;
     else
     {
      y=y+inc;p=p+2*(dy-dx);
      }
     x++;
     if(current==0&&c==10)
     {
      current=1;c=-1;
     }
    if(current==1&&c==6)
     {
      current=0;c=-1;
    }
    c++;
    }
  }
  else
 {
  p=2*dx-dy;
  if(y1<y2)
  {
   y=y1;x=x1;end=y2;
   if(x1<x2)inc=1;
   if(x1>x2)inc=-1;
  }
  else
  {
   y=y2;x=x2;end=y1;
   if(x2<x1)inc=1;
   if(x2>x1)inc=-1;
  }
  while(y<=end)
    {
    putpixel(x,y,15);

    if(p<0)p=p+2*dx;
    else
    {
     x=x+inc;p=p+2*(dx-dy);
      }
      y++;
      if(current==0&&c==10)
      {
        current=1;c=-1;
      }
      if(current==1&&c==6)
      {
       current=0;c=-1;
      }
      c++;
    }
  }
}

void main()
{
 float x1,x2,y1,y2;
 int ch;
 int gd=DETECT,gm=DETECT;
 initgraph(&gd;,&gm;,"");
 printf("Enter end points of line(x1,y1,x2,y2)");
 scanf("%f%f%f%f",&x1;,&y1;,&x2;,&y2;);
 printf("Choose Algorithm(1-DDA 2-BRESENHAM)");
 scanf("%d",&ch;);
 if(ch==1)
 dda(x1,y1,x2,y2);
 if(ch==2)
 bress(x1,y1,x2,y2);
 getch();
 closegraph();
}

xyz@xyz:~/comp304$ gcc  ddabr.c
/tmp/ccIKH395.o: In function `dda':
ddabr.c:(.text+0xd9): undefined reference to `putpixel'
ddabr.c:(.text+0x13d): undefined reference to `putpixel'
/tmp/ccIKH395.o: In function `bress':
ddabr.c:(.text+0x2c5): undefined reference to `putpixel'
ddabr.c:(.text+0x435): undefined reference to `putpixel'
/tmp/ccIKH395.o: In function `main':
ddabr.c:(.text+0x4dc): undefined reference to `initgraph'
ddabr.c:(.text+0x4e8): undefined reference to `grprintf'
ddabr.c:(.text+0x514): undefined reference to `grscanf'
ddabr.c:(.text+0x520): undefined reference to `grprintf'
ddabr.c:(.text+0x534): undefined reference to `grscanf'
ddabr.c:(.text+0x593): undefined reference to `grgetch'
ddabr.c:(.text+0x598): undefined reference to `closegraph'
collect2: ld returned 1 exit status