First, you can use FromOADate as a static method on the DateTime type. This method receives one double value as its parameter, and the returns a full DateTime. This will convert those five-digit integers to the regular DateTimes.
DateTime
Array We see an array of OADates you might encounter. Typically the doubles will be somewhere in the 30,000s, but you may encounter outliers.
Array
Next It loops with foreach through each example string. We use a foreach loop to look at each number in the array.
Foreach
Info These numbers would be typically be extracted from Microsoft Excel Interop or some databases.
Excel
FromOADate We show some example calls and output. With Console.WriteLine, we print the results.
Console
C# program that uses FromOADate
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 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.
Double
Finally We use the static DateTime.FromOADate to turn the double into a regular DateTime.
Static
Summary. We used the FromOADate method on the DateTime type in the C# language. We saw the input and output. This is a tricky topic and this article serves as an adjunct to my other Excel Interop article.
Note These methods are mainly required for legacy XLS files, which may be replaced with more robust XLSX XML files.