This program uses the midpoint circle algorithm to draw a circle in C++. It prompts the user to input the x and y coordinates of the circle's center point and the radius. It then initializes the graphics mode and uses the midpoint_circle function to draw the circle based on these inputs. The midpoint_circle function calculates the pixel coordinates on the circle using the midpoint algorithm and plots them. It also includes a show_screen function to display an interface for the user.

1. Code for Program to draw a circle using MidPoint Circle
Algorithm in C++ Programming
# include <iostream.h>
# include <graphics.h>
# include <conio.h>
# include <math.h>
void show_screen( );
void midpoint_circle(constint,constint,constint);
int main( )
{
int driver=VGA;
int mode=VGAHI;
int h=0;
int k=0;
int r=0;
do
{
show_screen( );
gotoxy(8,10);
cout<<"Central Point of the Circle : (h,k) :";
gotoxy(8,11);
cout<<"ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ";
gotoxy(12,13);
cout<<"Enter the value of h = ";
cin>>h;
gotoxy(12,14);
cout<<"Enter the value of k = ";
cin>>k;
gotoxy(8,18);
cout<<"Radius of the Circle : r :";
gotoxy(8,19);
cout<<"ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ";
gotoxy(12,21);
cout<<"Enter the value of r = ";
cin>>r;
initgraph(&driver,&mode,"..Bgi");
setcolor(15);
midpoint_circle(h,k,r);
setcolor(15);
outtextxy(110,460,"Press <Enter> to continue or any other key to
exit.");
int key=int(getch( ));

2. if(key!=13)
break;
}
while(1);
return 0;
}
/*************************************************************************/
//----------------------- midpoint_circle( ) --------------------------
///************************************************************************
*/void midpoint_circle(constint h,constint k,constint r)
{
int color=getcolor( );
int x=0;
int y=r;
int p=(1-r);
do
{
putpixel((h+x),(k+y),color);
putpixel((h+y),(k+x),color);
putpixel((h+y),(k-x),color);
putpixel((h+x),(k-y),color);
putpixel((h-x),(k-y),color);
putpixel((h-y),(k-x),color);
putpixel((h-y),(k+x),color);
putpixel((h-x),(k+y),color);
x++;
if(p<0)
p+=((2*x)+1);
else
{
y--;
p+=((2*(x-y))+1);
}
}
while(x<=y);
}
/*************************************************************************/
//-------------------------- show_screen( ) ---------------------------
///************************************************************************
*/void show_screen( )
{
restorecrtmode( );
textmode(C4350);
cprintf("n****************************************************************
****************");
cprintf("*-***********************- -
**********************-*");
cprintf("*------------------------- ");

3. textbackground(1);
cprintf(" MidPoint Circle Algorithm ");
textbackground(8);
cprintf(" ------------------------*");
cprintf("*-***********************- -
**********************-*");
cprintf("*-
***************************************************************************
*-*");
for(int count=0;count<42;count++)
cprintf("*-*
*-*");
gotoxy(1,46);
cprintf("*-
***************************************************************************
*-*");
cprintf("*----------------------------------------------------------
--------------------*");
cprintf("******************************************************************
**************");
gotoxy(1,2);
}