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Parsing and validating string dates

Parsing and validating string dates

If you have a string variable that should specify a date (asked in input to the user, for example), you can parse the string and get a Date variable by using the Date.Parse method. If the input string is not in a valid format, this method throws an exception though. Follows a routine that parses a string and sets a Date variable passed in input by reference, or returns False if the input string could not recognized as a valid date:

' Set the input Date variable by parsing the input string' Return true if the input string is not in a valid format' Example:'   Dim testDate As Date'   If String2Date(testDate, "12/25/2002") = True Then'       MessageBox.Show(testDate.ToLongDateString())'   Else'       MessageBox.Show("Invalid input date string")'   End If'   If String2Date(testDate, "12/35/2002") = True Then'       MessageBox.Show(testDate.ToLongDateString())'   Else'       MessageBox.Show("Invalid input date string")'   End IfFunction String2Date(ByRef retDate As Date, ByVal value As String) As Boolean    Try        retDate = Date.Parse(value)        Return True    Catch e As Exception        Return False    End TryEnd Function

You can write similar functions for other data types of course.

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