GraphDriver use At C++ OR OOP'S

#include<chandra.h>

// Global Variable Declaration..

int GraphDriver = DETECT; /* Request auto-detection */
int GraphMode;
void func_gen(float ,float ,float ,int, int, int);
void drawAxis();
void graph();
float mod(float );
void yx1(float );
void yx2(float );
float graphFunction(float );

//Main Function

void main()
{
initgraph( &GraphDriver, &GraphMode, "../bgi" );
    char c;
    int zoom_factor=10, xsh=0, ysh=0;
    float precision=0.01, min_range=-30, max_range=30;
    func_gen(precision,min_range,max_range,zoom_factor,xsh,ysh);
  do{
    c=getch();

    if(c=='w'||c=='W')
    {
      precision=precision/10;
      func_gen(precision,min_range,max_range,zoom_factor,xsh,ysh);
    }

    if(c=='q'||c=='Q')
    {
      precision=precision*10;
      func_gen(precision,min_range,max_range,zoom_factor,xsh,ysh);
    }

    if(c=='+')
    {
      zoom_factor +=2;
      func_gen(precision,min_range,max_range,zoom_factor,xsh,ysh);
    }

    if(c=='-')
    {
      zoom_factor -=2;
      func_gen(precision,min_range,max_range,zoom_factor,xsh,ysh);
    }

    if(c=='x' || c=='x')
    {
      ysh += 2;
      func_gen(precision,min_range,max_range,zoom_factor,xsh,ysh);
    }

     if(c=='s' || c=='S')
    {
      xsh += 2;
      func_gen(precision,min_range,max_range,zoom_factor,xsh,ysh);
    }

    if(c=='c' || c=='C')
    {
      ysh -= 2;
      func_gen(precision,min_range,max_range,zoom_factor,xsh,ysh);
    }

     if(c=='A' || c=='a')
    {
      xsh -= 2;
      func_gen(precision,min_range,max_range,zoom_factor,xsh,ysh);
    }

    if(c=='R' || c=='r')
    {
      ysh = 0;
      xsh = 0;
      precision = 0.1;
      zoom_factor=10;
      func_gen(precision,min_range,max_range,zoom_factor,xsh,ysh);
    }

    }
    while(c=='w'||c=='W'||c=='q'||c=='Q'||c=='+'||c=='-'||c=='s'||c=='S'||c=='x'||c=='X'||c=='a'||c=='A'||c=='c'||c=='C'||c=='r'||c=='R');

    closegraph();
}

//Mod Function

float mod(float x)
{
 if(x<0)
 return (-1)*x;

 else
 return x;

}

// COORDINATE AXIS

void yx1(float min_range, float max_range)
{

    float x=min_range;
    while(x<=max_range)
    { float y;

      y = x;


    float xcord=320+10*x;
    float ycord=240-10*y;
    if((xcord<=640 && xcord>=0) && (ycord>=0 && ycord<=480))
putpixel(xcord,ycord,50);
x += 0.1;
     }

}

void yx2(float min_range, float max_range)
{

    float x=min_range;
    while(x<=max_range)
    { float y;

      y = -1*x;


    float xcord=320+10*x;
    float ycord=240-10*y;
    if((xcord<=640 && xcord>=0) && (ycord>=0 && ycord<=480))
putpixel(xcord,ycord,50);
x += 0.1;
     }

}


void drawAxis()
{
      int i=0;
      while(i!=480)
      {   putpixel(320,i,1);
 i++;
      }

      i=0;
      while(i!=640)
      {  putpixel(i,240,1);
i++;
      }

}
/*
void graph()
{
int k=20, i=0;

     while(k<480)
     {
while(i<640)
{
 putpixel(i,k,5);
 i++;
}
i=0;
k += 20;
     }


k=20, i=0;

     while(k<640)
     {
while(i<480)
{
 putpixel(k,i,5);
 i++;
}
i=0;
k += 20;
     }
}
*/
void func_gen(float precision,float min_range, float max_range, int zoom_factor, int xsh, int ysh)
{
 cleardevice();
// graph();
 drawAxis();
 yx1(min_range, max_range);
 yx2(min_range, max_range);

  int color=(34);
  float x=min_range;
    while(x<=max_range)
    { float y;

      y = graphFunction(x);    //define a function
//   outtextxy(0,0,"Func_gen By Sunil Kumar Dheendhwal");

    float xcord=320+zoom_factor*x+xsh;
    float ycord=240-zoom_factor*y+ysh;

    if((xcord<=640 && xcord>=0) && (ycord>=0 && ycord<=480))
putpixel(xcord,ycord,random(color));
x=x+precision;
    }
}


float graphFunction(float x)
{

return x+10;

}