c# 简单计时器,开始,停止,清零,并有时间间隔,显示从开始到停止的所用时间-C# simple timer, start, stop, reset, and a time interval, according to the time from start to stop

利用VS c#实现的打卡时间计算器,具有统计，导出时间表的功能等(Using VS c# to achieve the clock time calculator, with statistics, export schedule functions)