C Program For Bressenhams Line Drawing Algorithm 

Source Code:

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

void bshmLine(int x1,int y1,int x2,int y2)
{
 int x=x1,y=y1,dx,dy,s1,s2;
 int length,i,dp,temp,swap=0;

 putpixel(x1,y1,WHITE);
 dx=abs(x2-x1);
 dy=abs(y2-y1);

 if(x2x1) s1=1;
 else s1=0;

 if(y2y1) s2=1;
 else s2=0;

 dp=2*dy-dx;
 if(dy>dx)
 {
  temp=dx;
  dx=dy;
  dy=temp;
  swap=1;
 }
 for(i=1;i<=dx;i++)
 {
  if(dp<0)
  {
    if(swap) putpixel(x,y=y+s2,WHITE);
    else putpixel(x=x+s1,y,WHITE);
    dp+=2*dy;
  }
  else
  {
   putpixel(x=x+s1,y=y+s2,WHITE);
   dp=dp+2*dy-2*dx;
  }
 }
}

void main()
{
 int x1,y1,x2,y2;
 int gdriver = DETECT, gmode;
 initgraph(&gdriver, &gmode, "c:/tc/bgi");

 printf("Enter the starting co-ordinates: ");
 scanf("%d %d",&x1,&y1);
 printf("Enter the ending co-ordinates:   ");
 scanf("%d %d",&x2,&y2);

 bshmLine(x1,y1,x2,y2);
 getch();
}