主题：请问如何确定两个日期之间有几个星期一？

没有的，只能自己写代码：

Dim dt1 As Date = #1/1/2012#
Dim dt2 As Date = #5/20/2012#
Dim dt As Date
Dim cnt As Integer
For i As Integer = 0 To (dt2-dt1).TotalDays
    dt = dt1.AddDays(i)
    If dt.DayOfWeek = 1 Then
        cnt = cnt + 1
    End If
Next
output.show(cnt)

=====================

這太低效了吧!

Dim dt1 As Date = #1/1/2000#

Dim dt2 As Date = #12/1/2012#

Dim n1 As Integer

n1 =dt1.DayOfWeek

dt1 = dt1.addDays(1-n1 )

dt2 = dt2.addDays(1-n1)

n1 = Int(((dt2-dt1).TotalDays+1)/7)+1

If  dt2.DayOfWeek = 1 Then n1+=1

Output.Show(n1)