In C# Does using File.OpenRead() needs to be closed?

user_2359957 0
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I did not find info about https://docs.microsoft.com/en-us/dotnet/api/system.io.file.openread?view=netcore-3.1

I'm checking if the file exists so that it is ready to be used. I will open the file soon later again. And I'm wondering if it is a better practice to close it after making the check.

Do I need to close the file after File.OpenRead()?

bool DoesFileOpensAndRead(string path)
{
    try
    {
        using (File.OpenRead(path))
        {
            return true;
        }
    }
    catch (Exception)
    {
        return false;
    }
}
c#
3 Answers

Since you are using the IDisposable interface through the using statement, you do not need to call Close, Dispose will do that for you.

user_235280
user_116278790

You do not NEED to close it - it will be closed automatically AT SOME POINT.

BUT: if you actually want to release the file lock that you created without waiting possibly for the next computer restart (or, technically more correct: until someone closes the program and the OS releases the file lock) then yes, you should delete it. This is not a "need" though (same as locking your car in a parking space is not a "need" - you likely get robbed at some point, but you do not need to lock it).

Now, your code example is more funny - it does not work. Period.

Your File.OpenRead is automatically DISPOSED at the end of the function. This is what the using statement does, and using is also internally closing the file. I am just not sure what the sense is as you are not actually doing anything with the file handle. You are WAY better of to not open read but - RTFM.

I'm checking if the file exists so that it is ready to be used.

Ah, yeah. Why not do it with the method that does that?

https://docs.microsoft.com/en-us/dotnet/api/system.io.file.exists?view=netcore-3.1

File.Exists is identical, in particular because "open it soon" is no guarantee that the file

  • is still there when you use it
  • CAN be opened when you use it.

Open does do some additional checks (can you actually read it, from the permissions?), but

  • There is no guarantee that these permissions are in place at he time of test (note how you say "soon," not "immediately"
  • The conditions may change before you open.
user_2854650
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