如何确保日期有效？

Question

我下面的代码将文件名的某些部分分配给变量。这里重要的是变量“yearandmonth”，它是一个格式为“yyyy-mm”的字符串

Dim fileparts() As String
            Dim delimiter As String = " - "
            Dim company As String
            Dim type As String
            Dim bank As String
            Dim bankaccount As String
            Dim yearandmonth As String 
            Dim fileyear As String
            Dim filemonth As String

            fileparts = Split(localFileName, delimiter)
            company = fileparts(0)
            type = fileparts(1)
            bank = fileparts(2)
            bankaccount = fileparts(3)
            yearandmonth = Left(fileparts(4), 7) ' RESULTS IN A STRING THAT WILL LOOK LIKE "yyyy-mm"
            fileyear = Left(yearandmonth, 4) ' results in "yyyy"
            filemonth = Right(yearandmonth, 2) ' results in "mm"

如何确保“yearandmonth”的输出是有效的年、月并且包含“-”？

Answer 1

您可以使用 DateTime.TryParse 方法来验证日期字符串是否是有效的日期格式，如下面的代码：

Dim dateStrings() As String = {"yyyy-mm"}
Dim dateValue As Date

If DateTime.TryParseExact(mystring, dateStrings, CultureInfo.InvariantCulture, DateTimeStyles.None, out dateValue) Then
    'Do for Valid Date
Else
    'Do for Invalid Date
End If