MFC 的几个常用函数，用来计算文件大小，下载速度，转换时间的

//获取文件的大小，并以KB 或 MB 来表示
CString GetFileSize(LONG size)
{
	CString _size;
	//判断大小有没有超过1
	if (size<(1024*1024))
	{
		_size.Format("%.2lfKB",size/1024.0);
	}else if(1024*1024*1024)
	{	
		_size.Format("%.2lfMB",(size/1024.0)/1024.0);
	}else 
	{
		_size.Format("%.2lfGB",(size/1024.0/1024.0)/1024.0);
	}
	return _size;
}
//获取下载速度的字符串
CString GetFileTranSpeed(DWORD size,DWORD time)
{
	CString _speed;
	//判断时间是否为0
	if (time>0){
		if (size/1024*1000.0/time<1024)
			{
				_speed.Format("%.2lfKB/s",size/1024*1000.0/time);
			}else 
			{	
				_speed.Format("%.2lfMB/s",(size/1024)*1000.0/time);
			}
	}else
	{
		return _speed = "0KB/s";
	}
	return _speed;
}
//获取时间的字符串
CString GetTimeFormatStr(LONG time)
{
	CString _time;
	int hh = time/3600;
	int mm = (time-hh*3600)/60;
	int ss =  time%60;
	_time.Format("%d%d:%d%d:%d%d",hh/10,hh%10,mm/10,mm%10,ss/10,ss%10);
	return _time;
}