Can someone please explain to me what this does.....

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Hi, I have been using a guide to help me write a small c# based excel application and have come accross a line of code that I have no idea what it acctualy does. IF someone could give me a brief explanation that would be great.

object misValue = System.Reflection.Missing.Value;
xlWorkBook.Close(true,misValue,misValue);

I don't really understand how (what) misValue actually does.

Thanks in advance

Dan

Posted 10-Jul-11 22:17pm

DanHodgson88

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Sergey Alexandrovich Kryukov · Accepted Answer · 2011-07-10T22:25:00

Solution 1

In means this: http://msdn.microsoft.com/en-us/library/system.reflection.missing.aspx[^].

Missing represents a parameter which is used by default if default parameter feature is used. Default parameters were introduced in C# v.4, but the mechanism itself already existed before. If the parameter is omitted, it is equivalent to passing a default value of the parameters. However, through Reflection, this parameter is not known to the caller. What to do? This is no any special value like null. A default parameter is specified by the author of the method to be called. Through Reflection, System.Reflection.Missing.Value should be passed.

—SA

Posted 10-Jul-11 22:25pm

Sergey Alexandrovich Kryukov

Updated 12-Jul-11 4:22am

v3

Comments

DanHodgson88 11-Jul-11 4:30am

cheers for that :)

Sergey Alexandrovich Kryukov 11-Jul-11 4:36am

Thank you, Dan.
--SA

Uday P.Singh 11-Jul-11 4:38am

correct answer my 5 too!!

Sergey Alexandrovich Kryukov 11-Jul-11 5:05am

Thank you, Uday.
--SA

DanHodgson88 11-Jul-11 4:39am

Thats great SA much Appreciated :) - Dan

Sergey Alexandrovich Kryukov 11-Jul-11 5:05am

You are welcome.
Good luck, call again.
--SA

Monjurul Habib 11-Jul-11 7:15am

nice answer, my 5.

Sergey Alexandrovich Kryukov 11-Jul-11 10:44am

Thank you, Monjurul.
--SA

Espen Harlinn 12-Jul-11 10:10am

Nice reply, my 5

Sergey Alexandrovich Kryukov 12-Jul-11 10:16am

Thank you, Espen.
--SA

CDP1802 · Accepted Answer · 2011-07-10T22:28:00

Solution 3

I think this page in the MSDN will shed some light on it:

http://msdn.microsoft.com/en-us/library/system.reflection.missing.value.aspx[^]

Such questions can usually be answered quickly with the help of Google :)

Posted 10-Jul-11 22:28pm

CDP1802

Comments

DanHodgson88 11-Jul-11 4:32am

cheers for that :) yeh you are right it was a bit of a "google" question. I had already looked at both your links and still struggled to understand what it does. msdn doesn't really explain it in "English" very well! Appreciate the reply though mate. I think I need to look at the constructor for xlWorkBook.Close for more info. :)

Sergey Alexandrovich Kryukov 11-Jul-11 4:36am

Frankly, it's all right. From this MSDN page it is not immediately clear. I tried to explain things.
--SA

Sergey Alexandrovich Kryukov 11-Jul-11 4:35am

I already answered a while ago.
Please see: I also added explanation.
--SA

[no name] 11-Jul-11 4:37am

I have never worked with it, but from what I have seen 'Missing' a singleton class which contains information on missing parameters in method calls. That is possible since there may be parameters in method calls which have a default value. If you call the method and omit the params with default values, they are missing and have to be replaced by the default values.