Array Console DateTime double Excel Interop foreach static

`FromOADate`

Excel interop dates are stored as integers. It is possible to convert them to DateTimes. We use FromOADate to convert OLE Automation Dates to real DateTime values.

We examine the FromOADate method. OA refers to "OLE Automation" and these are 5-digit numbers that represent a date and time.

Example

First, FromOADate receives one double value as its parameter, and the returns a full DateTime. This will convert those 5-digit integers to the regular DateTimes.

Start We see an array of OADates you might encounter. Typically the doubles will be somewhere in the 30,000s, but you may encounter outliers.

Next It loops with foreach through each example string. We use a foreach loop to look at each number in the array.

Info These numbers would be typically be extracted from Microsoft Excel Interop or some databases.

Here We show some example calls and output. With Console.WriteLine, we print the results.

using System;

class Program
{
    static void Main()
    {
        var arr = new string[]
        {
            // OA Dates in early 2008.
            "39456", // (1/9/2008)
            "39482",
            "39484",
            "39493",
            "39496",
            "39497",
            "39501",
            "39506",
            "39510",
            "39513",
            "39515",
            "39521", // (3/14/2008)
            // Different series starts here.
            "36526", // (1/1/2000)
            "36557", // (2/1/2000)
            "39270"  // (7//7/2007)
        };

        foreach (string b in arr)
        {
            // We must have a double to convert the OA date to a real date.
            double d = double.Parse(b);

            // Get the converted date from the OLE automation date.
            DateTime conv = DateTime.FromOADate(d);

            // Write to console.
            Console.WriteLine("{0} = {1}",
                b,
                conv.ToShortDateString());
        }
    }
}39456 = 1/9/2008
39482 = 2/4/2008
39484 = 2/6/2008
39493 = 2/15/2008
39496 = 2/18/2008
39497 = 2/19/2008
39501 = 2/23/2008
39506 = 2/28/2008
39510 = 3/3/2008
39513 = 3/6/2008
39515 = 3/8/2008
39521 = 3/14/2008
36526 = 1/1/2000
36557 = 2/1/2000
39270 = 7/7/2007

Values

Values must be double types. The FromOADate method requires that it receive a double value. For the custom code above, we convert the string to a double. You may not need to do this.

Finally We use the static DateTime.FromOADate to turn the double into a regular DateTime.

39456
39482
39484
36526
36557
392701/9/2008
2/4/2008
2/6/2008
1/1/2000
2/1/2000
7/7/2007

We used the FromOADate method on the DateTime type in the C# language. We saw the input and output. These methods are often required for legacy XLS files.