Parsing Non-Standard Date Formats

Bill is faced with the challenge of importing data into Excel that was originally created in other applications. The problem is that the data contains lots of dates, but they are in a format that Excel doesn't understand. For instance, the dates may be in the format 02.01.07 or 2.1.2007, neither of which is treated as a date by Excel. Bill wants to know how to convert the non-standard dates to a date format that Excel understands.

If the dates are in the same sequence format that you use in your regional settings, then converting is a snap. For instance, if your regional settings use the date format MDY (month followed by day followed by year), and the date you are importing is in the same format, then you can simply select the cells and replace the periods with a slash. When Excel changes 2.1.2007 to 2/1/2007, it automatically parses the result as a date.

If the format you are importing doesn't match your regional settings, then you need to shuffle around the date into the same format. For instance, if the date you are importing is 02.01.07 (February 1, 2007), and your system would interpret this as January 2, 2007, then the easiest way is to separate the date into individual components, and then put them back together. Follow these general steps:

1. Insert three blank columns to the right of the date column.
2. Select the cells containing the non-standard dates.
3. Using the Text to Columns Wizard (Data | Text to Columns or, in Excel 2007, choose Text to Columns from the Data tab of the ribbon), choose delimited data and use a period as the delimiter. After the wizard is done, you end up with three columns containing the month, day, and year.
4. In the remaining blank column, enter a formula such as the following:

     =DATE(C1,A1,B1)

5. Copy the formula down to other cells next to the dates.
6. Select the cells containing the formulas you just created, then press Ctrl+C.
7. Use Paste Special to convert the formulas to results. (Select the Values option when using Paste Special.)
8. Delete the three columns that contain the separated dates, and keep the column that contains the final dates.

Another solution is to simply use a macro to do the conversion. The following is a user-defined function that takes the non-standard date and converts it to a properly formatted date value. The macro also switches around the position of the month and day, as done in the Text to Columns technique.

Public Function Convert_Date(A As String) As Date
    Dim K As Long
    Dim K1 As Long
    Dim K2 As Long

    K = Len(A)
    K1 = InStr(1, A, ".")
    K2 = InStr(K1 + 1, A, ".")
    Convert_Date = DateSerial(Val(Mid(A, K2 + 1, _
      K - K2 + 1)), Val(Mid(A, K1 + 1, K2 - K1)), _
      Val(Mid(A, 1, K1 - 1)))
End Function