Cannot declare a variable of static type 'System.IO.File' in c# .net file upload

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hello pls help me..... i am using the code is

Scripting.FileSystemObjectClass f = new Scripting.FileSystemObjectClass();
Scripting.Folder Fld;
System.IO.File fl = default(System.IO.File);
Excel.Application xlapp = new Excel.Application();
Excel.Worksheet xlsheet = new Excel.Worksheet();

but i got a error is " Cannot declare a variable of static type 'System.IO.File'"
please help me

Posted 20-Jan-12 17:45pm

RAMALINGAM.K

Updated 4-Jun-20 22:45pm

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Sergey Alexandrovich Kryukov · Answer 1 · 2012-01-20T18:39:00

Solution 2

Yes, this type is static. Not only you cannot create and instance of such type, but apparently you also never need it. :-)

If your are trying to suck line like System.IO.File fl = default(System.IO.File);, you apparently have no idea what the class is, no matter static or non-static. Nothing can help here but systematic study of programming in general and OOP in particular. Try to get to a basic language and .NET manual and read it from the very beginning, doing exercise as you go, until the problem has gone too far. There is no other way.

Just a hint: you never need your fl, which cannot even exist. Instead of it, you always should use System.IO.File.*, where '*' is any method or property of this class. But you should not do it without understanding of what are you doing; and you apparently lack this understanding, so… see above.

In the meanwhile, just take a look at my past solution explaining this matter in detail:
What makes static methods accessible?[^].

It might at least give you an idea on what's involved. You may or may not understand it though. Than again… see above.

Good luck,

—SA

Posted 20-Jan-12 18:39pm

Sergey Alexandrovich Kryukov

Updated 20-Jan-12 18:53pm

v2

Comments

LosBear 11-May-12 13:19pm

Little harsh, don't you think?
He's posting his question 'cause he needs help, not to be berated. Still, you somewhat explain address the question, so I'm obligated to give you thumbs up =)

Sergey Alexandrovich Kryukov 11-May-12 13:48pm

Thank you.
Harsh? maybe. You say it as it's something bad. :-)
You know, I think this is the best help I could think of. After all, what's more important: to tell the truth or please someone? If both can be done, great, but what if the truth is not very pleasant. In some situation, I feel if I won't tell it, nobody will...
--SA

Member 10261821 20-May-14 12:31pm

how arrogant an answer can be...

Sergey Alexandrovich Kryukov 20-May-14 13:50pm

In some cases, it's important to talk this way. Let me ask you: would you rather prefer lie? :-)
—SA

Member 9962156 27-Jan-16 22:53pm

I know where you're coming from but honestly you're going to turn people away from asking questions and learning - not only the people you respond to in this fashion but all the people who are coming here for an answer, seeing things like this and saying "i'm out".

Don't ever forget where you came from - you did not come out of your mother writing code. Whether you learned on your own or someone taught you - I will bet my life you've asked someone a question about something you did not understand. Now imagine they made you feel stupid for asking and not much else. maybe you wouldn't know all the incredible things you know today.

Member 14088727 14-Dec-18 2:34am

No, you're just plain rude

Brandon Fitzgibbon 10-Apr-14 11:09am

The most helpful thing you could have done was point him towards FileStream or FileInfo if he wanted static objects that can hold file related data. If he's programming for Excel, he's probably just mixing something together real quick for work. Not everyone needs to be a top-down AAA programmer to build a helpful utility.

Sergey Alexandrovich Kryukov 27-Jan-16 23:03pm

Not true. Understanding fundamentals is primary thing, some particular classes — secondary. Some "help" is like urinating into pants on freezing air: at first, it feels warmer. Sorry for the rude joke. If a person don't understand the fundamentals, especially so simple, FileStream won't help. And even if it helps now, it's good only until the next static class or something similar and as trivial. Do you want our inquirers to remain inquirers forever?
"Most helpful"? Hm... I doubt it.

See also: Give a man a fish…. Can you see the point?

—SA

Member 10257418 18-Feb-22 4:57am

This was really unnecessary and a waste of time and energy for everyone. we all come here to find details and you sent to read an abstract book. I appreciate what you wanted to do but it was not really constructive.

User 1138000 · Answer 2 · 2012-01-20T18:38:00

Well, that pretty much describes the nature of the error in a very neat and explicit fashion: you cannot declare a variable to hold a reference to an instance of static class, because static classes cannot be instantiated, in the first place.

I think what you're looking for is the FileStream class, you can get an instance of this class in several ways; calling File.Open() with the appropriate arguments is one of them.