我们在项目中，有时需要定时执行某些功能，比如每天定时备份数据，或处理一些日终程序等。这里我主要是就VB中的Timer控件来介绍下。Timer控件的最重要的一个属性就是时间间隔属性（Interval）。它是以ms（微秒）为单位，范围0～65535。

这里有个时间的例子，如下：

主要用到的控件有PictureBox,名称属性设置为“PicTime”，还有三个文本框，分别为TxtYear，TextMth，TextDay，还有个用来显示时间的Label，名称为LblTime。布局如下：

定义全局变量：

Dim day,year,month,ddate,ttime As String

Dim alf(0 To 11)

Dim rr

Dim nHourLen,nMinLen,nSecLen As Integer

Const Pi = 3.1415926

设定Timer间隔时间为1秒：

Private Sub Form_Load()

Timer1.Interval = 1000

End Sub
Timer事件：

Private Sub Timer1_Timer()

rr = PicTime.Height / 2

ddate = Format(Now,"mm:dd:yy")

ttime = Format(Now,"hh:mm:ss")

month = Left(ddate,2)

day = Mid(ddate,4,2)

year = Right(ddate,2)

hh = Left(ttime,2)

mm = Mid(ttime,2)

ss = Right(ttime,2)

TxtYear.Text = "20" & year

TxtMth.Text = month

TxtDay.Text = day

LblTime.Caption = Time

nWidth = PicTime.Width - 40

nHourLen = nWidth * 4 / 18

nMinLen = nWidth * 6 / 18

nSecLen = nWidth * 8 / 18

alfsec = ((ss - 15) / 30) * Pi

alfmin = ((mm + ss / 60 - 15) / 30) * Pi

alfhour = ((hh + mm / 60 + ss / 3600 - 15) / 6) * Pi

PicTime.Refresh

For I = 0 To 11

alf(I) = I * 30 * Pi / 180

PicTime.DrawWidth = 1

If I = 0 Or I = 3 Or I = 6 Or I = 9 Then

PicTime.DrawWidth = 3

End If

PicTime.Line (rr + (rr - 100) * Cos(alf(I)),rr + (rr - 100) * Sin(alf(I)))-(rr + (rr - 300) * Cos(alf(I)),rr + (rr - 300) * Sin(alf(I))),RGB(255,255)

Next I

PicTime.DrawWidth = 3

PicTime.Line (rr,rr)-(rr + nHourLen * Cos(alfhour),rr + nHourLen * Sin(alfhour))

PicTime.DrawWidth = 2

PicTime.Line (rr,rr)-(rr + nMinLen * Cos(alfmin),rr + nMinLen * Sin(alfmin))

PicTime.DrawWidth = 1

PicTime.Line (rr,rr)-(rr + nSecLen * Cos(alfsec),rr + nSecLen * Sin(alfsec))

PicTime.DrawWidth = 5

PicTime.PSet (rr,rr),255)

End Sub

运行结果如下：

参考：《Visual Basic从入门到精通》