Bresenham circle drawing algorithm program in c

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

void main()
{
int gd=DETECT,gm;
int r,x,y,p,xc=320,yc=240;

initgraph(&gd,&gm,"C:\\TC\\BGI");
cleardevice();


printf("Enter the radius ");
scanf("%d",&r);


x=0;
y=r;
putpixel(xc+x,yc-y,1);

p=3-(2*r);

for(x=0;x<=y;x++)
{
if (p<0)
{
y=y;
p=(p+(4*x)+6);
}
else
{
y=y-1;

p=p+((4*(x-y)+10));
}

putpixel(xc+x,yc-y,1);
putpixel(xc-x,yc-y,2);
putpixel(xc+x,yc+y,3);
putpixel(xc-x,yc+y,4);
putpixel(xc+y,yc-x,5);
putpixel(xc-y,yc-x,6);
putpixel(xc+y,yc+x,7);
putpixel(xc-y,yc+x,8);

}
getch();
closegraph();
}

Bresenham line drawing algorithm program in c

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

void main()
{
int dx,dy,x,y,p,x1,y1,x2,y2;
int gd,gm;

clrscr();

printf("\n\n\tEnter the co-ordinates of first point : ");
scanf("%d %d",&x1,&y1);
printf("\n\n\tEnter the co-ordinates of second point : ");
scanf("%d %d",&x2,&y2);

dx = (x2 - x1);
dy = (y2 - y1);

p = 2 * (dy) - (dx);

x = x1;
y = y1;

detectgraph(&gd,&gm);
initgraph(&gd,&gm,"c:\\tc\\bgi");
putpixel(x,y,3);

while(x <= x2)
{
if(p < 0)
{
x=x+1;
y=y;
p = p + 2 * (dy);
}
else
{
x=x+1;
y=y+1;
p = p + 2 * (dy - dx);
}
putpixel(x,y,3);
}
getch();
closegraph();

}

Digital Differential Analyzer Line drawing algorithm program in c

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

void main()
{
int gd=DETECT,gm;
int x1,x2,y1,y2,dx,dy,l,i;
float delx,dely,x,y;
clrscr();
initgraph (&gd,&gm,"C:\\TC\\BGI");
printf("Enter the co-ordinates of the first point \n");
printf("x1= ");
scanf("%d/n",&x1);
printf("y1= ");
scanf("%d/n",&y1);
printf("Enter the co-ordinates of the second point \n");
printf("x2= ");
scanf("%d/n",&x2);
printf("y2= ");
scanf("%d/n",&y2);
clrscr();
dx= x2-x1;
dy= y2-y1;
if (abs(dx) > abs(dy))
l = abs(dx);
else
l = abs(dy);
delx=(float)dx/l;
dely=(float)dy/l;
x=x1;
y=y1;
for(i=0;i<l;i++)
{
putpixel (x,y,6);
x=x+delx;
y=y+dely;
}
getch();
closegraph();
}