一种函数指针的运用

定义一个结构体，称之为消息

//定义一种结构体，即消息
struct MSGMAP_ENTRY 
{
	UINT nMessage;
	LONG(*pfn)(HWND, UINT, WPARAM, LPARAM);

};

定义函数指针数组

//消息与处理例程的对照表
struct MSGMAP_ENTRY _messageEntries[] =
{
	WM_CREATE, OnCreate,
	WM_PAINT,OnPaint,
	WM_SIZE,OnSize,
	WM_COMMAND,OnCommand,
	WM_SETFOCUS,OnSetFocus,

};

调用

#define dim(x) (sizeof(x)/sizeof(x[0])) //计算数组的大小


//处理函数
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	int i;
	for (size_t i = 0; i < dim(_messageEntries); i++)
	{
		if (message == _messageEntries[i].nMessage)
		{
			(*_messageEntries[i].pfn)(hWnd, message, wParam, lParam);
		}
	}
}