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How do you convert Excel Date type to DateTime in .NET?

Posted on 2007-07-25
Medium Priority
Last Modified: 2013-12-17
am using the Office Primary Interop Assemblies (automation) to access an
Excel file from .NET and get cell contents. I'm using C#.

When I get the cell contents that contains an Excel Date value, I am having
trouble converting from the object variable type to DateTime.
The following error is displayed:

               The specified cast is invalid.

Here's the code with error:

Range rng = (Range)oSheet.get_Range("A4", Type.Missing);
System.Object myvalue = rng.Cells.Value2; //Assign it to an object var
DateTime dt = (DateTime)myvalue;

So how do I cast the retrieved cell contents to .NET DateTime?
Question by:TALJr
LVL 13

Expert Comment

ID: 19572142

Author Comment

ID: 19572173
How does this apply to what I described?
It looks like it solves a problem different from what I asked.
LVL 13

Expert Comment

ID: 19572248
you can parse the input string from the excel file as described in the link
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LVL 29

Expert Comment

by:David H.H.Lee
ID: 19572315
Dear TALJr,
You can write your own custom format accordingly regarding the datetime that retrieved from cell content. Anyway, you can amend it based on the cell value that you retrieved.
//myvalue.ToString() = 2007-7-26 1:00:PM <-- your cell content value for example.
DateTime dt=Format(CDate("2007-7-26 1:00:PM"), "dd,MM yyyy hh:mm:tt")
For more details regarding custom format date, you can check here:

Author Comment

ID: 19575144
The myvalue.ToString()  value is not even close to the format you have given as an example. I don't have it right now( (I'm out of my office) but it is a large integer: something like  127879.
Would this be days after some start date? It is definitely not seconds or milliseconds.

This is not .NET DateTIme, but Excel Date type.


LVL 96

Accepted Solution

Bob Learned earned 1500 total points
ID: 19575241
Excel uses the serial date concept, based on 1/1/1900.  The value for 1/1/1900 is 1.  Today's date is 39289.

You need a function like this:

public static DateTime DateSerialToDate(int value)
    DateTime dt = new DateTime(1900, 1, 1);
    return dt.AddDays(value - 2);


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