主题：文本转日期

参考代码

dim str as string = “2017-01-01”
Dim d As Date
If Date.TryParse(str, d) Then
    If d < Date.today Then
        msgbox("日期小于今天")
    End If
    Dim sp As TimeSpan = Date.Today - d
    msgbox("相差" & sp.TotalDays)
Else
    msgbox("日期无效")
End If