HWAD hwnd,hwnd|;
//variable that will store handle to window MSG msg;
//variable to contain message information
wc.cbsize=sizeof(WNDCLASSEx);
//cbsize should contain the size of the structure itself
wc.style=Cs_HREDRAW|Cs_VREDRAW;
//style specifies the class style
wc.IpfnWndProc=WNDProc;
//WndProc is pointer to WndProc() function 
wc.cbClsExtra=0;
//Specifiec the number of extra bytes to allocate following the window_class structure
wc.cbWndExtra=0;
//Specifies the number of extra bytes to allocate following the window instance
wc.hInstance=hInstance;
//Handle to application instance
wc.hIcon=LoadIcon(NULL_IDI_APPLICATION);
//LoadIcon function gives handle to the icon that the int const IDI_APPLICATION represents.
//hIcon member of wc refers to the icon shown when ALT+TAB is pressed.
//First parameter of LoadIcon=Handle to an instance of module whose executable file contains the icon.
//   to be loaded.this parameter must be NULL when a standed icon is being loaded
//Cursor refers to mouse pointer