# Program to draw a C-Curve of nth order

``` # include <iostream.h>
# include <graphics.h>
# include    <conio.h>
# include     <math.h>

void show_screen( );

void C_curve(long double,long double,long double,long double,int);

void Line(const int,const int,const int,const int);

int main( )
{
int driver=VGA;
int mode=VGAHI;

long double x=0;
long double y=0;
long double l=0;
long double angle=0;

int n=0;

do
{
show_screen( );

gotoxy(8,10);
cout<<\"Starting Point of the Line : (x,y) :\";

gotoxy(8,11);
cout<<\"ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ\";

gotoxy(12,13);
cout<<\"Enter the value of x = \";
cin>>x;

gotoxy(12,14);
cout<<\"Enter the value of y = \";
cin>>y;

gotoxy(8,18);
cout<<\"Length of the Line : l : \";
cin>>l;

gotoxy(8,20);
cout<<\"Angle of the Line with x-axis : \";
cin>>angle;

angle*=(M_PI/180);

gotoxy(8,22);
cout<<\"Enter the Order of C-Curve = n = \";
cin>>n;

initgraph(&driver,&mode,\"..\\\\Bgi\");

setcolor(15);
C_curve(x,y,l,angle,n);

setcolor(15);
outtextxy(110,460,\"Press <Enter> to continue or any other key to exit.\");

int key=int(getch( ));

if(key!=13)
break;
}
while(1);

return 0;
}

//------------------------------  C_curve( )  ---------------------------//

void C_curve(long double x,long double y,long double length,
long double angle,int n_order)
{
if(n_order>0)
{
length/=M_SQRT2;

C_curve(x,y,length,(angle+M_PI_4),(n_order-1));

x+=(length*cosl(angle+M_PI_4));
y+=(length*sinl(angle+M_PI_4));

C_curve(x,y,length,(angle-M_PI_4),(n_order-1));
}

else
{
setcolor(getcolor( ));
Line((int)(x+0.5),(int)(y+0.5),
(int)(x+length*cosl(angle)+0.5),
(int)(y+length*sinl(angle)+0.5));
}
}

//-------------------------------  Line( )  -----------------------------//

void Line(const int x_1,const int y_1,const int x_2,const int y_2)
{
int color=getcolor( );

int x1=x_1;
int y1=y_1;

int x2=x_2;
int y2=y_2;

if(x_1>x_2)
{
x1=x_2;
y1=y_2;

x2=x_1;
y2=y_1;
}

int dx=abs(x2-x1);
int dy=abs(y2-y1);
int inc_dec=((y2>=y1)?1:-1);

if(dx>dy)
{
int two_dy=(2*dy);
int two_dy_dx=(2*(dy-dx));
int p=((2*dy)-dx);

int x=x1;
int y=y1;

putpixel(x,y,color);

while(x<x2)
{
x++;

if(p<0)
p+=two_dy;

else
{
y+=inc_dec;
p+=two_dy_dx;
}

putpixel(x,y,color);
}
}

else
{
int two_dx=(2*dx);
int two_dx_dy=(2*(dx-dy));
int p=((2*dx)-dy);

int x=x1;
int y=y1;

putpixel(x,y,color);

while(y!=y2)
{
y+=inc_dec;

if(p<0)
p+=two_dx;

else
{
x++;
p+=two_dx_dy;
}

putpixel(x,y,color);
}
}
}

//--------------------------  show_screen( )  ---------------------------//

void show_screen( )
{
restorecrtmode( );
textmode(C4350);

cprintf(\"\\n********************************************************************************\");
cprintf(\"*********************************-           -**********************************\");
cprintf(\"*--------------------------------- \");

textbackground(1);
cprintf(\" C-Curve \");
textbackground(8);

cprintf(\" ----------------------------------*\");
cprintf(\"*********************************-           -**********************************\");
cprintf(\"*-****************************************************************************-*\");

for(int count=0;count<42;count++)
cprintf(\"*-*                                                                          *-*\");

gotoxy(1,46);
cprintf(\"*-****************************************************************************-*\");
cprintf(\"*------------------------------------------------------------------------------*\");
cprintf(\"********************************************************************************\");

gotoxy(1,2);
}
```

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