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What is the difference between File and FileInfo in C#?

Posted by: admin November 30, 2017 Leave a comment

Questions:

I’ve been reading that the static methods of the File Class are better used to perform small and few tasks on a file like checking to see if it exists and that we should use an instance of the FileInfo Class if we are going to perform many operations on a specific file.

I understand this and can simply use it that way blindly but I would like to know why is there a difference ? What is it about the way they work that make them suitable for different situations ? What is the point of having this 2 different classes that seem do the same in different ways ?

It would be helpful if someone could answer at least one of this questions.

Answers:

Generally if you are performing a single operation on a file, use the File class. If you are performing multiple operations on the same file, use FileInfo.

The reason to do it this way is because of the security checking done when accessing a file. When you create an instance of FileInfo, the check is only performed once. However, each time you use a static File method the check is performed.

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“The methods of the File and FileInfo classes are similar, but they differ in that the methods of the File class are static, so you need to pass more parameters than you would for the methods of the FileInfo instance. You need to do this because it operates on a specific file; for example, the FileInfo.CopyTo() method takes one parameter for the destination path that’s used to copy the file, whereas the File.Copy() method takes two parameters for the source path and the destination path.”

http://www.aspfree.com/c/a/C-Sharp/A-Look-at-C-Sharp-File-and-FileInfo-Classes/1/

http://www.intelliott.com/blog/PermaLink,guid,ce9edbdb-6484-47cd-a5d6-63335adae02b.aspx

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Answers:

The File.Exists will perform much faster than a new FileInfo(filePath).Exists – especially over a network and provided the files actually exist. This is because File.Exists will only check for existence of the file, whereas a new FileInfo(filePath).Exists first constructs a FileInfo object, which contains all the properties (dates, size etc) of the file (if it exists).

In my experience with this, even checking for the existence of 10 files over the network is noticeably faster (ie 20ms vs 200ms) by using File.Exists.

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File is optimized for one-off operations on a file, FileInfo is optimized around multiple operations on the same file, but in general there isn’t that much difference between the different method implementations.

If you want to compare the exact implementations, Use Reflector to look at both classes.

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A FileInfo may be needed to deal with Access Control properties. For the rest it is a Static versus Instance choice and you can pick what is convenient.

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Yes, and one of the reason could be is, as Nag said Files is a utility class and hence no instance is required to be created. Same time, as File being utility class, each time require security check.

On other hand FileInfo requires instance to be created, and that point it uses security check. Thus, now performing multiple operation using FileInfo will not invoke security checks.

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FileInfo is an instance of a file thus representing the file itself. File is a utility class so can work with any file

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Recently I faced problem with File.Exist, I hate this function. After than I’ve used Fileinfo class Exist function then my program works correct.

Actually what happen in development enviornment File.Exist works well but when it goes to live environment this function is blocking the file object due to that reason I am getting the error access denied and not able to use the file.

This is my learning.
I will never used File.Exist method best is to create the object and then use it. Be aware to use static methods.