VC++ Program using Menu control

#include <Windows.h>

#include "resource.h"

long _stdcall myfunc(HWND,UINT,UINT,long);

WNDCLASSA a;

HINSTANCE hi;

HDC d;

HPEN  hp;

void color();

int c;

int _stdcall WinMain(HINSTANCE i,HINSTANCE j,char *k,int l)

{

      HWND hwnd;

      MSG m;

      a.style=CS_HREDRAW|CS_VREDRAW;

      a.lpfnWndProc=myfunc;

      a.hInstance=i;

      a.hbrBackground=(HBRUSH)CreateSolidBrush(RGB(500,400,60));

      a.lpszClassName="my";

      a.lpszMenuName=MAKEINTRESOURCEA(IDR_MENU1);

      RegisterClassA(&a);

      hwnd=CreateWindowA("my","Controls",WS_OVERLAPPEDWINDOW,100,100,20,20,0,0,i,0);

      ShowWindow(hwnd,3);

      while(GetMessage(&m,0,0,0))

            DispatchMessage(&m);

      return 0;

}

long _stdcall myfunc(HWND w,UINT x,UINT y,long z)

{

      const POINT pt[10]={250,150,250,300,300,350,400,300,320,190};

      int c=5;

      switch(x)

      {

            case WM_COMMAND:

            {

                  switch(y)

                  {

                        case RECTANGLE:

                              d=GetDC(w);

                              color();

                              Rectangle(d,120,100,50,70);

                              ReleaseDC(w,d);

                              break;

                        case LINE:

                              d=GetDC(w);

                              color();

                              LineTo(d,100,100);

                              break;

                        case ROUNDRECT:

                              d=GetDC(w);

                              color();

                              RoundRect(d,890,60,70,300,30,40);

                              break;

                        case ELLIPSE:

                              d=GetDC(w);

                              color();

                              Ellipse(d,1000,60,90,500);

                              break;

                        case CHORD:

                              d=GetDC(w);

                              color();

                              Chord(d,200,300,800,500,400,500,700,300);

                              break;

                        case POLYGON:

                              d=GetDC(w);

                              color();

                              Polygon(d,pt,c);

                              break;

                        case STAR:

                              d=GetDC(w);

                              color();

                              break;

                        case BLUE:

                              c=1;

                              color();

                              break;

                        case RED:

                              c=2;

                              color();

                              break;

                        case GREEN:

                              c=3;

                              color();

                              break;

             }

            }

             break;

       case WM_DESTROY:

             PostQuitMessage(0);

             break;

       default:

             return DefWindowProc(w,x,y,z);

             break;

  

   }

       return 0L;

}

void color()

{

      switch(c)

      {

       case 1:

             hp=CreatePen(PS_SOLID,3,RGB(0,0,250));

             SelectObject(d,hp);

             break;

     case 2:

             hp=CreatePen(PS_SOLID,3,RGB(250,0,0));

             SelectObject(d,hp);

             break;

       case 3:

             hp=CreatePen(PS_SOLID,3,RGB(0,250,0));

             SelectObject(d,hp);

             break;

       default:

             hp=CreatePen(PS_SOLID,3,RGB(0,0,250));

             break;

      }

}